Before the 2020 Democratic presidential primaries completely fade into the mists of memory, it is worth recalling that Mike Bloomberg spent a staggering $1.1 billion to run for president badly. Very badly.

The former New York City mayor never even hit the 20 percent mark in a single primary. And his grandest moment came when he (drum roll, maestro) swept the caucuses in American Samoa.

Despite Bloomberg’s epic flameout, politicians and strategists in both parties (plus the reporters who cover them) stubbornly refuse to accept the truth articulated by the Beatles nearly a half-century ago: “Money can’t buy me love.”

Many political scientists have long been skeptical about the lasting electoral value of television ads — especially early ones. In their enduring study of the 2012 president race, “The Gamble,” John Sides and Lynn Vavreck concluded, “Most of the effects of campaign advertising wear off quickly.”

Despite this history, both parties have entered the era of wretched excess when it comes to campaign spending. CNN reported last week that over $100 million has already been spent in five key Senate races. In 2014, in contrast, the five most expensive Senate races in the nation cost a total of $225 million over the entire campaign.

None of this is designed to suggest that congressional candidates should refrain from using any advertising medium more expensive than sandwich boards. Or that a country that spends $40 billion annually on pet food can’t afford robust political races.

But candidates and donors alike should ask themselves a simple question: “How much is enough?”

At what level of spending does an extra dollar fail to have any effect on vote totals? And is there a point when the omnipresence of a candidate’s TV ads annoys voters so much that it actually costs votes?

The analytical difficulty here is that no major candidate is willing to run his or her campaign as an empirical test of the value of additional TV buys. So ridiculous levels of spending ($277 million squandered in the small state of South Carolina on the 2020 Senate race) are maintained because any fundraising restraint is viewed as the equivalent of unilateral disarmament.

Campaign consultants, of course, are in no position to offer the campaigns they serve disinterested advice on the value of an unending TV advertising blitz. For many of these operatives, their compensation is directly tied to how much a campaign raises and spends.

The problem for candidates is that desperately scrounging for money when you already have enough to wage a competitive race raises the odds that the newest contributions will come with lobbyist strings attached.

Donors, for their part, can be suckered into tossing money down political sinkholes like the $94 million sent to Democrat Amy McGrath in her hopeless (38 percent of the vote) 2020 Kentucky Senate race against Senate Republican leader Mitch McConnell. It is staggering to think of the number of state legislative races that $94 million might have won.

Speaking of McConnell, one of the few passions in his political career (other than rubber-stamping conservative Supreme Court justices) has been his unyielding opposition to any form of campaign reform. His objections are rooted in his constitutional conviction that any form of regulation is bad — for Republicans.

But McConnell has ignored the overriding lesson of 21st century politics: No tactical advantage lasts very long.

It took less than a decade after the “Citizens United” Supreme Court decision for the Democrats to master unregulated campaign fundraising. As The New York Times reported over the weekend, the Democrats raised as much — if not more — than the Republicans in non-disclosed “dark money” during the 2020 campaign cycle.

While some of this Democratic advantage was sparked by antipathy to then-President Donald Trump by the uber-wealthy, it also directly flows from how far to the right the GOP has moved on social issues. In billionaire circles on Park Avenue and in Silicon Valley, there is scant support for Republican election conspiracies, book banning or the Supreme Court overturning Roe v. Wade.

Still, given the GOP’s lockstep opposition to any campaign spending disclosure requirement, it was hard to resist giggling while reading a Monday press release from the National Republican Senatorial Committee. Accusing Senate Democrats of “constant hypocrisy,” the NRSC called upon five incumbents on the ballot in 2022 to stand by their commitment to banning “dark money.”

Of course, the NRSC offered no hint that the Republicans would join in any effort to prevent anonymous donors from dominating politics. Even when both parties have reached parity in off-the-books fundraising, the GOP — more out of habit than logic — still refuses to embrace reform.

Over the weekend, the New York Legislature moved to the cusp of approving a gerrymandered redistricting map likely to cost the Republicans four House seats. In their opposition to anything that smacks of independent redistricting commissions, the GOP once again failed to recognize that Democrats, too, can play hardball in allocating House seats.

Republicans keep making the same mistake. Fueled by Trump’s frenzied opposition to voting by mail, Republicans have been working overtime to restrict absentee balloting in states like Georgia and Texas. The result may end up costing Republicans the votes of elderly white voters who are daunted by new ID requirements.

In a rational world, we may be close to the point of parity when it is in the self-interest of both parties to embrace ambitious campaign reform. But because of habit, stubbornness and partisan mistrust, such an accord is about as likely as Senate candidates willingly running no-frills campaigns.