There's many reasons why windows machines sell more then Macs. Multiple vendors is of course one major reason.
What I'm seeing somewhat is more people choosing to buy windows machines instead of macs for various reasons. A couple of reasons I've come across, is value, i.e., price/features but mostly because the macs are not doing what they want. Windows machines always had an edge on using faster components, now for the past few years computer makers are designing some really nice looking machines. So now we have good looking computers that run faster then Macs and are typically cheaper then macs, either through regular pricing or perpetual discounts.
I think Apple focused on iDevices so long and largely ignored laptops/desktops that other companies were able to swoop in and woo customers who would have purchased macs. Add in the incredible negatively towards apple design choices from 2016 and beyond (Touchbar, butterfly keyboard) and that just alienates more people.
Apple is selling a lot of macs, I'm not arguing that they're doomed, but I am saying to some degree the bloom is off the rose, they don't have the same allure as they used too. Even the hackintosh sector has seemingly quieted down, I have no numbers to back up my opinion, but it seems there's less of a draw to make hackintohes. Only Mac users not willing to buy a mac are mostly interested in hackintoshes.