They are looking at few things in no particular order:
1) A large sum in the bank.
2) Assets in Thailand, such as houses, condos, etc.
3) Employment status. Business owner or a higher level position with a large company.
4) Education. Where you went to university in Thailand. Really helps if you have been educated overseas.
5) Travel to other countries. It really helps if you have been to other European countries, Australia, Canada, etc.
6) Family in Thailand.
As has been said earlier, the 10 year visa just means that you don't have to re-apply for a visa for 10 years. I think the maximum time you can spend in the US on a 10 year visa is six months. They are also looking to see if you are likely to return to Thailand after your visit to the US. That's why having traveled to other countries and returned helps as I listed in #5.