We are talking about people who come here, maybe have a condo rented for a year, and are bouncing/running out and back into the country after a day or 2, every couple of months. Some countries allow longer stays, but most countries expect you to leave at some point if you are a tourist. And if you are staying in a resort for 5 months, you are living at that resort.
You can get a 6 month multi entry tourist visa, or a retirement type visa for longer stays, which is what immigration was telling the OP.
Tourism means exploring the country. If you only show up at one address, that is not tourism. I myself have been using Thailand as a base for exploring SE Asia, and am exploring Thailand as well. My passport is full of country stamps.
When I leave, sometimes I am gone weeks at a time, but even I am waiting for that warning now. But I am soon heading back home for a good while.
Basically, whatever you are doing, to them, it looks like you are residing in Thailand, not touring Thailand.
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.