There is no discernible mass groundswell for an Eric Swalwell presidential campaign.

The case against: He is a 38-year-old California congressman of little legislative distinction. He would appear to have minimal running room in a deep and accomplished Democratic field expected to grow to 20 or so — large enough to fill two baseball starting lineups, with another contender or two left to heckle from the dugout.

The case for: Why not?

“We don’t have time for vanity things,” Mr. Swalwell insisted in an interview this past week, the morning after he announced his candidacy on “The Late Show With Stephen Colbert,” pledging to anchor his bid in a call for greater gun control. “We’re doing big things.”

That remains to be seen. But at the very least, if recent history is a guide, a run is likely to yield better things, perpetuating the victory-in-defeat incentive structure endemic to modern presidential politics.

Today’s primaries tend to produce one nominee but many winners. Beyond the long-shot candidates effectively auditioning for cabinet positions or building a profile (and donor base) for future races, there are prospective books to sell and television contracts to sign, boards to join and paid speeches to paid-speak. Any setback is temporary, any embarrassment surmountable.