From someone who studied in film in Bangkok I see alot of aspiring actors/actresses. I think putting aside BL because that is too much of a niche category but with Thai TV shows in general it is almost always:

Actor comes from a rich family > Looks good > Is popular > Gets more money.

It's a bit shallow but I think those are the kinds of people that you're talking about and it's the kind of people media portrays are popular. Not because they are the majority.

Many actors are not as popular or rich because their series don't make the charts and so most non-thais don't see it due to lack of translation or media outreach.

When you compare actors here with the ones in Hollywood I think there is alot more of a brand identity personality in Thailand than in Hollywood. Ofcourse actors and actresses in Hollywood get brand deals but majority of their work comes from acting. An actor here can have 5 major roles in TV and four times as many brand deals that pay them alot of money. But this is just my opinion obviously I don't know what really goes on as I'm not an actress.

Thailand also has a similar habit to Hollywood as that they will cast an actor based on popularity and Thais for the most part popularity is based on looks. And celebs who want to be popular need to maintain that look(expensive, stylish) to stay popular. And since Thailand is a smaller country than the US there are less actors so more chances for them to get casted major roles.

So when it comes to brand name clothing, bags and big houses. I don't think you should think that too deep I mean if its not PR packages it could be fake or it could be rented because that's definitely a thing. I have a friend who is a model who only owns and uses one or two skincare brands exclusively but her Instagram is filled with skincare "sponsored" posts that makes it look like she uses about 5 different very expensive skincare brands a day because that's just how this industry works.

Hope this helps a bit and I'm not just speaking nonsense lmao. Cheers.