Reader question: Raising the ground to build a house

Dear Happy Man,
according to your own description you should, or want, to raise about 2.5m. That's not a little, but a lot. I don't know how far the adjacent houses are from your construction site. If very close to it, then I would certainly not pile because there is a great risk that these homes will suffer damage due to the pile driving and the resulting vibrations.
The fact that water regularly remains on the lower lying terrain does not mean that the soil is unstable. It may well be that this is a substrate that is impermeable or difficult for water to penetrate, eg a layer of clay.
How I would handle it:
for raising you have a few pits dug. You don't have to be a structural engineer to determine whether this is muddy ground or stable ground. If, in your opinion, it is a well-established soil layer, then, in places where you would otherwise have to drive piles, make sufficiently large pits to pour a foundation saddle. You can then raise this, with formworked piles, to just above the building level and then rest the later concrete platform on it. Before you start building, you can still raise the ground between these poles, after all, it no longer has to support anything.

I am not an architecture specialist - I do know that we built a house in 2004 in the moon-river bed (around Phimai) that house was built with my knowledge and equipped with a basement.
To date, the basement is still waterproof (see nuisances in the past), the house itself does not yet show any settlement cracks.
Build on sufficiently strong foundations - search / ask for information - at Western architecture and you will certainly succeed in your intentions,
Another thing, many Thai contractors would like to gain knowledge about Western construction techniques.
Some are stubborn – then look further for someone who is open to other techniques.
Don't let yourself be influenced/forced by local customs (read family) - do remain open to their vision and solutions.
With some patience and your own input you will certainly get good results.
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Hammering in/drilling posts seems like a pointless thing to me. after raising > 2 meters, waiting until 2 years is recommended. Check it out after a rainy season…..