Can I extend my stay in Thailand every 6 months for 5 years with the DTV?

You can extend every 6month stay by another 6month.

That means after 12month you have to leave and come back.

If you cannot afford to leave the country, you should not be staying in Thailand.

Pretty sure soon there will be services where only your passport leave the country

Just out of curiosity: why such a simple question posted in anonymous status?

I mean i would understand if you write: i dont want to pay taxes. But this one? 👀

You can enter Thailand as many times as you want and stay for up to 180 days each time without any additional fees during the duration of the visa. There is not a rule saying only 180 days per year. Go in and out as many times as you want with 180 day stamp each time.

If you wish to stay in the country and not leave within the 180 days then you can apply for an extension of an additional 180 days. No one has done this yet because 180 days hasn't passed since the inception of this visa. There is some debate on what this extension will cost due to some wording in the English and Thai language descriptions of the visa from the MFA. Many assume it will be the same 1900 baht fee while others suggest that it might be 10,000 baht. I personally believe it will be 1900 baht but no one is 100% sure at this time. The only reason the extension fee will matter is if you don't plan to leave the country within 180 days.

For me, the extensions are a bit irrelevant because I will travel out of the country occasionally and reset the 180 day count for free each time.

This video explains everything about the DTV and what you want to know.

Rent a car and cross the border, u-turn and come back saying you forgot your wife home. And yes, only 1 extension per entry

Depends what suits you. If no current desire to exit Thailand, you live in the centre of the country and it would cost $40 or $52 USD to enter Laos (for example), a 180 day extension for 1,900 baht from your local Immigration Office may be preferable.

I would personally forget the hassle of extending and spend a few days in a neighbor country every 6 months and reset the 6 months counter !!

At this time extensions aren't recommended as there is no real world experience on the extension requirements, a border bounce for a new 180 day stamp is the preferred choice until reports of extension experiences have begun rolling in.

Yeah only one extension per visit then have to leave country

One extension in-country per entry. So you have to leave Thailand after 360 days. You then re-enter with 180 days which you can extend another 180 days on that entry.