Your Intel based Mac will be relevant and working just fine in 2025 even, based on what happened during the PPC to Intel switch, I don't see any huge risks here.
Some people just like having the latest. I tend to buy a new iPhone every 2 years, and a new Mac every 4 years.
I found out I really enjoy working with the latest hardware. I'm enjoying a decent income and now upgrade to the latest base model every 2-3 years.
If you get the 13 inch models, they have extremely good resale value and thus make it (relatively) affordable.
The first-gen Apple Watch was also fine.
Personally I'd wait to see what comes out this fall, and buy then. They'll most likely release new Intel Macbooks in addition to any ARM offerings.
So as far as I am concerned, the first Apple CPU in a mac will be a no-go beta device, that will be much better at the second generation.
Also, regarding the OS, we are not really yet aware of all the things that are going to break with the architecture change: it's not a switch to ARM but a switch to Apple. There's a huge lot of possible problems for a device I'll need running at 100% for my work.
list of recalls: https://support.apple.com/en-asia/exchange_repair
and there is a lot of bugs that apple don't even admit. (ex, ghosting screen on some macbookpro retina ( first version )
Support for Macs is certainly longer term, so feature change between years shouldn't be that dramatic, but shipping anything for the first time at Apple's scale means they're going to stumble upon optimizations they missed the first time around. For that alone, I would avoid buying a first-gen Apple Silicon Mac.