@Emily *******
I got asked the question one time during a Laos border run *why are u border run u been Thailand long time!* or wtv, can't remember exactly. I just said that I have a *thai GF, she is right there! (pointing)*, and officer reply *wife, oh!*, with a big smile!
If for some reason that answer doesn't work, just say that u have *invested money years ago and it work out very well!*. Don't go more into details, doesn't matter if it's stock market, Bitcoin or wtv, stay vague. I've been ask one time in 5 years...
I even make a new passport in BKK canadian embassy recently, last one only lasted 2.5 years before running out of pages. I didn't know what to write under job in the document, I didn't put that I have invested money, I put *unemployed*. Lady then review document with me, I said *unemployed*, she didn't ask any further question. So even if i've been in Thailand for long time she didn't doubt my answer, they can't.
Everybody financial are different, someone could have a rich family, won the lotto, made good investment, work illegally, or have a thai BF-GF that pay for everything. It's nobody business and if officer ask which is very rare there is plenty of answer that will be fine. No need to talk about investment, or gray area, go with the *I have a thai BF and a baby*, 99% of the time there will be no further question.