Is it risky to apply for a DTV visa myself in Indonesia, and what are the success rates for cooking classes versus Muay Thai?

DTV application question: I plan to do it in Indonesia (Bali or Jakarta, not sure if it matters), is it risky if I apply myself or should I do it through an agency? How long does it take to process the visa from Indonesia? Whats the success rate if I apply under Muay Thai vs Cooking class (preferred for me, i actually love cooking)?

If I go with an agency, which ones are reliable and has a decent price? I talked to an agency and their price is more than other ones and they said I can only go do it in Vietnam (don't prefer to go bc it traumatized me a little in the past) and only apply for Muay thai bc they have a partnership and that cooking classes won't get approved. I feel like they just want me to do this so their partner gets my money for muay thai (my partner wants to do muay thai but I don't bc i am unable to do it physically due to health reasons and I've done it in the past when I was able to).

Also if I opt for a cooking class like do I have to look for a place that would agree that I would use them for a DTV visa? Whats the success rate for this? I'm actually serious about cooking though, how come muay thai always gets approved and cooking classes don't have the same success rate?

Let me know if you have successfully applied from Indonesia with a cooking class or muay thai option or any good agencies (not willing to spend a lot for this since I can technically do it myself).

Thanks