Seriously, OP never mentioned investing in a business equipment but wanting a camera. Also, that camera will depreciate no matter how you paid for it, but you conveniently mentioned it only in the scenario 1.
For the rest I actually agree with you and think credit system is predatory and that if one can, one should take advantage of it. Just that buying something on credit because want, and using that something to earn money are two fundamentally different cases.
Having my funds reduced to 91% the rest of the year is waaay worse for me, than having it reduced to ~0% the rest of the month. Because, the rest of that month, I'll be super-vigilant, I'll be acutely aware of why I have less money than normally, I know not to make anymore purchases, I know that this month is not for an extra treat, because I bought the other thing. Next month I'll be back up to 100% capacity.
This affects my model of my financial situation, because, it's a camera then.. ~91%, it's a new toaster there ~86% and then ~40% and ~20% and now I get into the dangerous "poor" mindset, it's well proven (and I can personally attest to this being a very real effect) that having less money makes it harder to be financially vigilant, there's opportunity cost* for once, but there's also a tendency to "treat" oneself more because things feel tight, there's a tendency to short-sighted savings (the more expensive pr roll toilet paper, versus the cheaper bulk option that has higher up-front cost for instance).
Now, to begin with, I'd go into "savings" mode a month before buying something expensive, so that I'm not at ~0% for a month, I'd never do that.
* Sure, there could be 100% opportunity cost right after paying in full for something, but the recovery to full capacity is also quicker. I really prefer the large, immediate consequences over the smoothed-out slow-squeeze.
1) Buy for cash the camera now. You don't have any cash in hand afterwards, and the camera is depreciating in value immediately as an asset only offset by whatever you do with it.
2) Buy via BNPL with no interest for 12 months, and pay exactly a 12th a month. You have the camera, but you also have 91% of your cash in the bank that /does/ get interest or can be used for anything else like investing in shares. You still have liquidity and can assumedly use the camera to generate some cash doing weddings or whatever as part of your hobby for one year.
3) Save cash where you are getting similar rates of interest as 2 for 12 months once you've identified you need something. Buy the camera a year after you needed it, you have lost the opportunity of 12 months revenue from maybe one wedding a month? The price is either affected by inflation after a year, or more hopefully its gone down due to competition with other models, but who knows. Also do you still need a camera? you've certainly lost out on a years experience to know if it was worth it.
BNPL makes plenty of sense if you can or cant afford something, more so if you can.