Number 7 is a university tournament.
that is not actually amateur, and I recall seeing Hao Shaui once at these tournaments before
These players have proper foundation and also very likely feature in the domestic league structures, of the Jia A, B etc
I don't follow the domestic leagues in China any more, but I won't be surprised some of these players are in Jia B/C
and for the "older" players, then they are likely former league players too.
Amateur in many countries is more like your conventional club players who doesn't train 40 hours a week for few years (in the juniors age group)
These "amateur" are likely those ones who didn't make the cut for provincial main member, but have the skills to be good enough to actually make another countries national team.
Its crazy how much high level numbers you actually get in the East