Help to moving to Seychelles, Maldives, Tahaa, or Raiatea needed :-)

Yes, you are naive!
First, you do need a job to pay for your intended lifestyle. Finding one as a foreigner is not easy in any of the locations mentioned, and in most, salaries are MUCH lower than what you are used to. E.g., a foreigner living the life you describe on a Thai island (Phi Phi or Phuket, probably the cheapest and most foreigner-friendly locations on your list) needs around THB40-60k (EUR1000-1500) a month, yet an average local earns THB10k. Which skills do you have that are rare and so much in demand there that it justifies paying you 4-6x more than them?
Second, because millionaires are globally mobile, beachside properties are expensive worldwide. You are more likely to stay in a highrise appartment near your workplace, with neighbours avoiding you (because, in local eyes, you are weird), and take an overcrowded bus to the beach once a week.
Third, snakes, spiders, cockroaches, ants and (mainly) mosquitoes are a natural part of the tropical climate you seek. To avoid them, stay on in the temperate zone. There is no other way! (Even keeping your appartment spot clean, high on incetizide, airconditioned cold, with all windows shut will not keep all of the critters out, believe me!)

In addition: Have you ever lived outside of your comfort zone? in a place where things don't work as you expected, or at all? Where you don't speak the language and cannot communicate with the people around you, maybe cannot even read the signs? Where the locals are more interested in your money than in you as a person? (Who can blame them if they are poor and you are not?)
Try this first for a while (e.g. a few months) to find out if it is right for you, before making a permanent decision. Many before you have tried and found the advantages of living in a civilized, organised and rich world is more compelling than a (mostly short-lived) urge to drop out of the "rat race".

Forget any of those places you mention in your post.

Not easy to get a work permit/visa for Thailand or anywhere in Asia for that matter. 

Hot humid snakes spiders.

Any of the Pacific or Indian Ocean island places are the same. No work for locals so no work for foreigners.

I speak from experience having spent last 47 years living, working and travelling around the world and many of the places you mentioned. 

Best take off the rose colored glasses you are wearing, start saving some money and perhaps travel to these places first.

Sorry to burst your bubble.

The cockroaches here are the size of Volkswagens.

it's not that impossible but each place has it's own set of problems. for starters, i highly recommend the french polynesia. i've lived in many countries and have traveled across the globe and there isn't a single place on earth that can compare in beauty etc.. thailand's a good place but you won't be getting your peace and quiet (although you could always go to lesser known islands eg. koh kood) but koh phi phi's packed with people and isn't very clean etc.. you'll find a hard time getting a job in thailand and getting a work visa. i can tell you how to go about getting your visa etc. but know that they don't make it easy in asia unless you're willing to leave the country 3 times a year but that's another headache altogether. the french polynesia (tahiti and it's islands) are snake free and in fact hardly has any animals apart from the stray dogs which you find in most islands including all over thailand etc.. but you can expect mosquitoes everywhere. on the other hand, tahiti's super expensive and if you happen to find a job in some hotel, then your wages might not be enough to save. infact you'll find that all of islands around the world have pretty much the same problems apart from the fact that some of them are super expensive. all i can say that at least in tahiti's case, you'll get the most beautiful of what the world has to offer but it comes at a very high price! now in thailand, you can pretty much survive on any kind of a budget but don't expect to get a job that pays  a lot. if you're lucky you might be able to score a job that pays around 300 euros a month...

What about Roatan? seems very reasonably priced for an island. or Bocas del Toro Panama? I was looking for island living too and I'm visiting both of those this year. I am most likely moving to Colombia though as so far it makes the most sense for me. I'll be visiting about 10-12 places in the next 12-18 months before deciding.. I would also suggest visiting before you plan a move or you may hate the place that you pick.