This comes down to language, specifically what differs an opinion from a belief. Which is quite complex and I cannot fully wrap my head around it. But here's my

This comes down to language, specifically what differs an opinion from a belief. Which is quite complex and I cannot fully wrap my head around it. But here's my take nonetheless. In this case, placing the "I think" would make it a belief. This could also make a statement an opinion, but from what I understand, beliefs have a non-zero chance of being proven or disproven, whereas opinions cannot be proven. "I think gentleman11 is nice username" is a bit different than "I think gentleman11 is a man". Something being "nice" is a bit harder to prove, and possibly impossible without additional context. Thus, it is an opinion. Someone being an man, cheater, alcoholic, etc have the ability to be proven, so it's not as much an opinion as a belief. I'm not a linguist, but I'd be interested in what language specialists have to say on this.