I don’t get it - what’s the market for an overpriced ( even by today’s standards ) non-upgradeable but “build it yourself” desktop pc? Is it because its a prebuilt server? Or just the fancy case?

I guess they made decent phones so that oppo had a foothold in western markets, but they got their asses handed to them by xiaomi. The moment xiaomi established themselves I swear oppo started phasing out oneplus. This has been a long time coming.