It's pretty easy to find out who I am in the real world too. For one thing I'm a private pilot and for 10 years I had an airplane personally registered to me, making my name and address a matter of (open) public record.
Look, I'm not wanting to be rude here, and this is obviously all hypothetical since you're likely not actively pitching to investors, but if you were, being stubborn in this way would be a deal breaker for me as an investor.
I see all the reasons you have for keeping it, and they're reasonable, but the mere idea that that's a hill you're willing to die on is a red flag. I'd see this as one of many potential points of friction. Where else will you choose to not make compromises?
Maybe it's not rational on my part, but you're trying to convince irrational entities to part with their money.
You could look at it this way: if someone offered $17M to change it, would you?
I wouldn't say the username is a hill to die on. I can't hide that this is the online identity I used while working on this project. Trying to hide it would just feel sketchier, no?
And yeah, for 17 mil I'm willing to talk about most anything, but I still see a conversation with investors like going on a date. The red flags can go both ways...
But fundraising is a game to be played, and part of playing the game is building credibility with VCs. It may be that a quirky name helps with that, but probably not.
From the classic baseball movie Bull Durham, where the old veteran is explaining to the newbie how to be successful:
"Your shower shoes have fungus on them. You'll never make it to the bigs with fungus on your shower shoes. Think classy, you'll be classy. If you win 20 in the show, you can let the fungus grow back and the press'll think you're colorful. Until you win 20 in the show, however, it means you are a slob."
If you already have a track record, then you can have a quirky name or personality. Until then, you've got to play the game.
Sure some people will rule me out for superficial reasons, but I also get some benefit in screening out people who want to kick the tires but aren't interested in building a real relationship, just like companies do when they screen job candidates.