Should I bring as much cash as I can when traveling to Thailand?
No, you are allowed upto USD20,000 or its equivalent out or into Thailand.
Source: Royal Thai Embassy
BRINGING CURRENCY IN OR OUT OF THAILAND
Any person who brings or takes an aggregate amount of foreign currency
exceeding USD20,000 or its equivalent out of or into Thailand shall
declare such amount of foreign currency to a Customs Officer.
Failure to declare upon bringing currency that exceeds the amount
restricted by law or its equivalent out of or into Thailand or making
any false declaration to a Customs Officer is a criminal offence.
Does it make sense to bring as much cash (up to 20k USD) as possible when going to Thailand?
No honestly you can carry upto 20k usd in Thailand , it is not a good idea to carry that much cash with you while traveling.
It's often a good idea to get some foreign currency before you leave home so that you have cash on hand to handle your immediate expenses -- like buying a meal at the airport or taking a cab to your hotel.
The best options are carrying credit cards/debit cards, travelers checks and very little amount of cash while you travel.