To win the Presidency, one needs only sway about 3% of voters.
95% of voters are going to vote a particular way regardless of who’s running.
Beto just alienated >1% of Democrats who, quietly, are pro-gun and aren’t going to support giving up their own “assault weapons”. That’s a big loss to ensure in the main race even before getting the Democrat nomination.
(Statistics used are scientific wild-a$$ guesses. Show me wrong.)
I'll bet he alienated a lot more than 1% of Democrat voters. Quite a few of them own firearms and support the right to keep and bear arms.