How much money do you need to show when entering Thailand to be allowed entry?

None. There is no such requirement, they do not ask for cash, bank cards, or bank statements. The most important things needed to enter Thailand are a valid passport and return tickets (they are not always checked, but they should be available). Nothing else at all. More details about the entry procedure to Thailand in this guide here - https://nashaplaneta.net/asia/thai/visas.html

Where to go in Thailand for the first time?
Do I need a category "A" license to rent a motorbike?
Can I exchange rubles in Phuket?
Follow the link, all these questions are discussed in the chat - https://t.me/thailand_travel_chat