As a farang you can drive whatever you want. But if you are involved in an accident you will be in the wrong. Insurance will mean diddly squat. Worthless. If you have not driven on the roads here then you need to be extremely careful when you do.
If you are accident prone or have poor health, then yes, get insurance. If you are like me and most other people on the planet, pharmacies have everything you need and hospitals are world class and cheap.