I'm going to give some seemingly counter-productive advice here: don't worry about being the best.  By all means, do NOT take this as "don't work hard to be an incredible whatever you want to do/be", I'm just saying what's more important is to find your voice and doing your best to make it heard.

Maybe reality IS that if you're not identified as a prodigy by age 4 the odds aren't in your favor about being Ray Chen, Hillary Hahn, or Chloe Chao.  That doesn't mean you can't write and play AMAZING music.  If I hadn't watched Chloe give Bret and Eddie from TwoSet Violin pointers about playing Paganini, I'd have no idea that there was any room for improvement in the way they play it (though the difference was like trying to tell apart a Texan accent and an Alabama accent by having two guys say the word "oil"; it's diminishing returns folks).  So they're not THE BEST but they HAVE found their voice as musicians and entertainers.  Their 4 Million Subscriber Mendelssohn with the Sydney Symphony was INCREDIBLE to watch.  All due respect to Ray but watching those two play was just more fun than just about any video or song of his; listening to Foggy Dew by Peakfiddler is more fun for me than a lot of the incredibly hard repertoires that virtuosos play that at a certain point just seem to be jumping around on the fingerboard, difficult just for the sake of being difficult.

Damien Escobar wasn't discovered until the age of 11 I believe, graduated Julliard early because of both talent and hard work, and frankly has the most beautiful rendition of Purple Rain I've ever heard (yes, I prefer it even above Prince's original version).

Maybe she wasn't wrong that your window on being the next generational virtuoso is closed because you weren't putting in 6 hours a day at 2 years old but that gives her absolutely NO RIGHT to ever be dismissive of you being talented, being skilled, being entertaining, and being INSPIRATIONAL.

I made the plunge into violin after stumbling onto TwoSet one day and them inspiring me to borrow my sister's used violin.  As I hope you noticed from my last comment, you're already pretty inspirational as well dude.  Forget the haters, find your voice, and spread the fun.