In case you haven't noticed, it wasn't a Democrat "win," it was more of a split decision. We didn't win the Senate, so Biden won't get to pass legislation we want, appoint judges we want, or even form a cabinet we want. Now what should we do about it? Senate has a bias towards small, rural states, which get same 2 senators as large urban states. We need to win those states to get the Senate so we can pass things that are important to us, and they aren't generally hot on gun control. Secondly, GOP won state legislatures, so they will continue gerrymandering Democrats into urban enclaves, meaning evenly split states like NC will continue having 70+% Republican House delegation, that is unless we go after the rural vote, in which case again, we would need to revisit gun control to appeal to those voters.
So we can be stuck on this gun control issue which we can't pass anyways, or we can ditch it, talk about issues that actually matter to most people across America, like health care and education, and actually build a majority party.
Finally, we shouldn't just have a debate on whether to push gun control as a political calculation, but also whether our current position on it still make sense in the rise of fascistic tendencies on the right that threaten to send this country into civil strife and armed mob rule. Trumpism isn't going away any time soon. Those people are still there, armed and on "standby," waiting for the next authoritarian personality cult leader to come along and give them orders. Maybe the next one won't be a bone spurs coward like Trump but a real thug. It seems like now is not the time to continue to unilaterally disarm and hope for the best.