...Because Belgium is bigger? If you think about, any of these guys we're bandying about might be safer in the luxurious and stable palaces of Vienna, Munich, etc.
Adolphe was in a different position than all the other guys, being the heir apparent to an existing throne. Abandoning the secure Nassau throne in favour of ahe insecure Belgian one in 1830-1831 would've been a very big risk. It was a new country, still rumbling from the events, which wasn't recognised by its Northern neighbour, which still risked losing the support of the great powers, some of them (Russia, Austria, Prussia) not being that enthusiastic about its existence in the first place, and with a hostile elite - a probable majority of it being opposed to independence, and a lot of those that were in favour or a seperation from the Netherlands were republican and/or pro-French, only accepting the monarchy because they had to.
Why would Adolphe take the risk of ending his days with no throne at all, if he can play on the safe side and stay in Wiesbaden? The other guys had a lot less to lose.
Also, being only 13 years of age doesn't really play into his advantage.