Most sites that sell or buy something are illegal because they do not pay taxes. Recently, many sites have needed to prove that the user is over 16 years old. Recently I decided to sell all my skins in cs go. Here https://globalcsgo.com/csgo-trading-sites/, I found the best site that buys skins. When registering, I had to prove that I was over 16 years old with a passport photo. To be honest, I was a bit surprised. I am glad that now children will not be able to spend their parents' money.