My advice would be don't go into something just because it looks like fun, or because you think you could do better; without having some real knowledge of how the business works. A great example if this is opening a bar or restaurant without prior experience working in and running one. Just because a person has spent years drinking in bars or eating in restaurants does not qualify them for running one (unless they just want a hobby that eats their money with no return).
E-commerce businesses will do well, although the barriers to entry mean you will face increasing competition and again, don't go into this unless you really know the product you are selling, have a solid reliable supply chain and you have someone who can help with the setup etc. We run a couple of shops on Lazada that make a few hundred thousand baht a month.
The question is what business experience do you already have? Is there something you are knowledgeable in that you could turn into a business here? The other question is why would you want to work if you don't have to?