50 btc just for changing my username.
Are you kidding.
He is not , 50 BTC = 50 BTC .
This forum has been created when Bitcoin has been created so BItcoin was cheap that time , most of people donated long time ago and have VIP accounts , but yeah since you are Junior you should simply create a new account instead of donating 50 BTC.
Yeah, it was cheap on past, but enpensive on present.
My suggestion :
Since you're still junior member (still not making deep effort to reach that rank ) , you can make a new account to change your name and decide your name carefully or you will regret again if you want to change your name again once you're hero member