While Apple will cut off the M1's machine live cycle in 2027, you can still use your machine with an updated Windows for a whopping 5 years longer
I wouldn't want to use a Mac with Bootcamp to begin with, in parts due to the lackluster Windows driver that Apple provides it's not an equally good experience. Battery life as well as bad trackpad support (palm recognition doesn't work well and is essential especially for a 16" Intel MBP that has a huge trackpad).
And you are basing all this on a random guess, nobody can tell how long M1 devices will be supported. Basing it on experiences with Intel Macs doesn't work too well either, we had Intels that were out of support after just 4 years or so and others that got updates for a good 8-9 years. So anything between 5 and 10 years goes. And installing the latest MacOS major version is not necessary, right now many users are still on Ventura or Monterey although these are technically no longer receiving all security updates and certainly won't get any feature updates. But apps continue to be supported, Monterey will start seeing issues with latest apps later next year or the year after, for my 2015 MBP that's now 8.5 years old it means you can use it another year or two before Monterey runs into issues with app compatibility.
Me randomly guessing that the M1 will see at least as much support as the longest Intel support suggests M1 will run the latest apps until 2029 or even 2030 on an older MacOS until it's done for. And then there might be some sort of OCLP support that allows newer MacOS versions to run on M1 unofficially. Like how my 2015 MBP is still able to run Ventura with OCLP just fine.
And if you are going to install Windows on an Intel Mac with bootcamp you could just give OCLP a try. If it's fully supported then the experience (again, battery, trackpad, and of course having native MacOS) will be much better than with Windows. I did use Windows with bootcamp before, and stopped after multiple times Windows Updates wouldn't run or once broke the entire install which made me quit using it as it was very obvious that neither Microsoft nor Apple care about a good bootcamp experience. And why would they. Microsoft would rather you buy a windows PC that comes with a bundled Windows license, and Apple would rather you remain in their software universe.
Getting more life out of an Intel Mac sounds like a great idea until you actually use it - maybe it's better on a desktop Mac that doesn't need that trackpad support and doesn't have a battery, I'll give you that. But for Macbooks where I had multiple with bootcamp, a 2012 MBP, a 2015 MBP and the last one a 2017 MBP before I dropped bootcamp it didn't work well enough on any.
For anyone who doesn't absolutely need Windows or MacOS there might be a linux based system with a relatively good UI available over the next couple of years. Bootable linux already exists for the M1 though complications with driver support for that M1 mean there is not guarantee when or if that will be ready for actual use. (I tried it on my M1 Mac many months ago and it was far from ready.)
Guys what’s crazy is for fun I looked at Best Buy. They will give me $675 on trade in for this thing. Imagine trading and making $275 on this lol.
That is something people do, though usually with phones. Specifically, there are trade-ins where you get ridiculous amounts for the iPhone SE and you just buy one off craigslist for 50 bucks and send that in.