@Chiripitiparty ************
When you want to stay for 5 years, you need a reason to stay for 5 years.
Because it is difficult to proof you need to stay 5 years, because it is unreasonable to ask for proof of 5 years soft power activity already at the moment of approval and an employment contract in a lot of cases also does not cover full 5 years, proof for a shorter period is accepted.
But when you only can proof a short time, obviously you are not determined what to do about the rest of the period and they might give you a visa that matches better with your purpose of stay.
It is completely up to the embassy to decide what visa you need.
DTV is not just a visa to live in Thailand, but a visa that allows you to visit the country for certain purposes for short stays of up to 180 days during 5 years.
If you just want to stay there are more appropriate visa.