1. You are planning to get an ED visa? If not, then,
2. I guess you will "Study" on a tourist visa, which would be illegal to do. But in any case,
3. Your airline may very well ask for proof of onward travel, which would need to be within the 60 days. Thai immigration may ask as well, but less likely. Those saying they have never been asked, have just never been asked. Plenty of other people get asked. They are actually asking more frequently these days. Just book a changeable flight before hand. I have actually received money back on a couple occasions when I changed dates.
I am Travelling SE Asia, with Thailand as my base. Trust me, your info is incorrect.
What you SHOULDN'T be doing is trying to live in Thailand on tourist visa/visa exemption. But even then it would probably take more than 2 trips for them to say something.
But it IS only 2 LAND border entries per calendar year.
I get asked all the time. I figure because, since I am travelling SE Asia, and using Thailand as a base, I am usually booking one way tickets. And it isn't just Thailand that asks. Many SE Asian countries ask now. This year, I have been asked at check in for flights to Singapore, Thailand, Cambodia, Laos, and Vietnam.