Even if you do change your username regularly, your patterns of speech may stay rather similar. And no matter what you say, the context around it may change in 30 years or so.
This new generation loves to screenshot personal conversations and then post them to Reddit for brownie points. Meaning if you get involved with someone who's slightly malicious, they can easily ruin your life too.
At this point I'm very careful to only meet folks in person. It's not unheard of for people to share compromising details about themselves, only to become extortion victims.