Should I rent a long-term apartment before applying for a DTV visa in Thailand?

No.

Nomads are known to change locations frequently.

I can’t answer for embassies in every country but I applied from India and didn’t book anything before applying, just mentioned a hotel I “intend” to stay at during my application process.

They asked me for additional documents which was proof of accommodation, at which point I booked a hotel for 1 month from Agoda using the “book now pay later” option. Sent them the booking confirmation receipt I got from Agoda. Along with this, I attached an “explanation note” which stated that this would be my base accommodation for the first month while I look for long term rentals as I didn’t wanna book a long term condo without physically checking it out.

I got approved the same day. If I have to be honest, I personally think I wouldn’t have had an issue getting approved even showing a booking for like a week, but since it was a refundable/pay later booking I had nothing to lose, so just went ahead with the 1 month booking.

Some specific Embassies in South East Asia (Malaysia? Vietnam?) reportedly demand you to have a lease, which is, in my opinion, ridiculous. I applied in my home country Korea and they wouldn't ask anything like that. They did wanted to see real plane tickets, tho. I also showed my hotel/Airbnb bookings for the first days. I've been so far 1 year in Thailand and I still DON'T have a lease. I change cities every here and then.

@Bi***

12-months is fine. But this visa attracts no bank account

We have just got a 6 month rental in chiang mai, move in nxt Monday then will be getting ready to do our dtv soft power.... Going Vietnam.

I’m wondering about this too. I don’t want to commit to rent in a place I might not be able to live in.