There's a lot of reasons why different people use Mac’s.
the main reason they became popular is that they were simple and streamlined. They are a compact clean and easy-to-use machine that became very very popular.
It became a lot about the image as well. companies that had iMacs lined up in the row for their employees to use. This looked very advanced and sophisticated. I feel that this gave an image of almost if you didn't have a Mac you are not a professional. This led to a very big wave of Mac purchases. I myself was one of them. And Mac’s are very nice, But there are a few major issues with them.
One of the biggest issues that I find with Mac’s is that they have very little Cooling. They just don't have big enough fans or enough fans, to keep the components that are that fast, cool enough.
One of the things that make Mac so easy to use, is that it is very restricting on software and components. This creates issues if you would like to purchase a Nvidia Graphics card for your Mac and run Octane. The other big reason I find is that Mac’s tend to be much more expensive, Compared to an equally equipped PC. pc also is much more compatible, It makes it much easier when choosing what type of CPU or GPU or Ram or motherboard you would like to use. This all said you could build your own Mac just like you could build your own PC. you would just simply have to install a Mac operating system instead of a Windows. you would still have restrictions though of making sure that you would use only be supported graphic cards and CPUs and RAM that Mac allows. but in the end, it would perform just as well as an equal equipped Windows PC and would cost the same. the only downside is it would be harder to make the Mac build as There would be more restriction in your part selection. Either way, whether you like Mac or PC you can make a build that will do what you needed to do it just may be a little harder if you choose Mac.