The person mentioned being denied entry before—that’s the answer. Anyone can be denied entry if they fail to meet the visa requirements or have committed something illegal here. That’s how it works everywhere. If you choose to risk your money knowing you’ve been denied before or commit an offense, that’s your decision. Personally, I’ve been questioned about my visa (not DTV), but since I had all the required documents, they allowed me in.
There is still a chance to obtain a visa even if you have been denied entry before. However, it’s important to note that a DTV is issued by the MFA (Ministry of Foreign Affairs), whereas the decision to deny entry is made by immigration authorities. Does having a DTV guarantee you entry into Thailand? No. Entry is ultimately at the discretion of immigration officers upon your arrival.
Many people misunderstand this process and assume that holding a visa guarantees entry, which is not the case. While I don’t know the specific reasons for your previous refusal, they may still apply now.