There's conflicting information about this. On the one hand, in-country extensions require a 500K THB bank balance. But advice from what I'd call official sources suggest otherwise. The Chiang Mai airport is requesting that new entries on the DTV prove only 20K THB balance. Also, someone recently posted a notice from one of the SEA embassies that there's no requirement to keep the 500K in your account after your application's approved.
If you are a salaried worker, things might be relatively smooth. However, don't apply if you've been working remotely for less than 6 months. However, if you are a sole proprietor, make sure to provide thorough documentation (tax receipts, invoices, portfolio, etc.), but by the same token, don't apply if you have less than six months' work history. If you are doing soft power, make sure you have additional consistent income (passive or earned) or a few multiples of the minimum funds banked. Note: this applies to Americans.
Maybe some schools which help you manage your visa application process would provide refunds, but It would make sense that they don't. How do they know anything about your immigration history or financials and your chances for acceptance?
I wonder if interviews are more popular at the Asian consulates because the applicants there are more likely to have been living in Thailand on ed visas or visa-free entries.
Is that going to be standard procedure at Chiang Mai from now on? Chiang Mai was my first port of entry on my DTV in November and I didn't get questioned. Hoping each subsequent entry won't be scrutinized. However, this suggests that the claims that you must always have 500K in your account at all times are overblown. Edited to clarify my post
A lot of people post about their worries about weaknesses in their application. Not sure how likely it is that visa officers lurk on this group, but it might lead to unwanted scrutiny.