No one forces anyone to upgrade on Day One. ;)
I bought a MacBook Pro "Early 2008" – the last model with the silver keyboard (how I still love it!) – a few weeks before the first "unibody" MacBooks were known to be released in October 2008, to replace a mere 3-years old PowerBook G4 that was already hopelessly obsolete by then but which I'm still keeping to run some PPC only software every now and then. The MBP ran Snow Leopard until 2019 (!) when I upgraded it to El Capitan – highest possible – after making sure all my important "obsolete" stuff will still run or is possible to convert or replace. Also: a 2TB SSD makes it fly. Partitioned to boot anything from Leopard to El Capitan.
I bought a MacBook Pro Mid-2012 – the last model with a CD/DVD-R drive (how I still need it!) and matte display (how I still can't be without it!) – in 2013, also a few weeks before the first "retina" MacBooks were known to be released. It ran Mountain Lion until 2019 when I bought a 2 TB SSD drive and partitioned it from Mountain Lion (skipping Mavericks & Yosemite) to Catalina, making El Capitan the primary partition to keep it easily in full sync with the 2008 MacBook.
Then I bought Helix Native last December while it was on sale combined with my HX Stomp discount, only to realize that it won't run in Logic 9. At the same time I also realized that I have the last chance to buy Logic X via Catalina before it will be Bug Sur only, so I finally upgraded to Logic X as well. That was a good move anyway because Logic 9 already has some stability issues on El Capitan, albeit manageable. I'm also slowly but steadily migrating my Adobe CS5 graphic work to the Serif Affinity suite because I won't join the Adobe CC rip-off, and while CS5 still works more or less stable on El Capitan, it won't run on Catalina. Neither will my trusty but also "obsolete" Firewire audio interfaces. Heck, M-Audio Firewire 410 works on El Capitan only thanks to user-hacked drivers, although the device is otherwise fully functional. Eventually I'll likely buy the Roland UA 1010 Octa Capture to replace the Alesis iO26 under Catalina.
And most importantly, I have no plans to replace this MacBook Pro Mid-2012 anytime soon. I'd rather spend a few hundred CHF to repair it in case anything will fail. And it will, sooner or later: I already had to have the keyboard replaced a few years ago. But it's still worth it, more than having to buy any of the new MacBooks, not to speak of Hackintoshs with their own tail of problems.
Or even moving to Windows; no way. Got a bunch of PCs last year from my late father who was a Windows "enthusiast", spending most of his time to keep them running in the first place, instead of doing any creative work while he still considered himself an "artist". They're waiting in storage to be thorughly inspected sometime later this year. I already shudder only thinking of having to deal with it. Love his LG display as an extension when plugging in the MacBook in my studio though. Eyesight vanishes with age, display size matters, 15" is not much…
Waiting for new MacBook Pros 15/16" with Sillicon chips, wondering how those will turn out. And for how much. The current 16" "Pro" [scare quotes] is of no interest for me. The major dealbreaker with all recent MacBooks: the non-replaceable SSD drive. Need 2TB or more. Won't pay Apple's "premium" for that.
But that's just me. Your mileage may vary. :)
Depending on which exact 2009 model, it can run either up to El Capitan or High Sierra. If the latter, you can still do practically anything with it. In some instances you'd only need to stick with an "older" version of software. But e.g. with Logic X, for me it's not a big deal having to use v10.3.3 on El Capitan. It does all I need already.
No one forces anyone to upgrade on Day One. Options exist! ;)