That's a bold statement. Especially without knowing the full set of facts. In this case, with your stance, you'd be the only computer in the place not on an Apple device. It's a small video/photography shop. Everyone involved uses a Mac including the freelance guys that get hired.

What exactly are proper tools? I'm designing a set of web-based tools to help their day to day operations. Lots of shell scripting and what not to just allow people to drag-n-drop and automagically get things to happen, consistently. Are you saying that the proper tool to write php/css/js/shell scripts/etc can only be found not on a Mac? I have found the world becomes a much easier place to live in if/when you can just accept what is on hand and get the job done. Could it be better? Possibly. Is this my favorite laptop? Nope. Can I do what I've been tasked with to get it done? Absolutely. I'm actually quite thankful that I'm not a one trick pony and I can use pretty much any OS put in front of me.

I can use mac if I'm forced to do but my sanity is worth more than some extra money I can get doing so

and seriously, using slow and noisy machine with poor multitasking and overall terrible UX WILL slow me down considerably, it's not worth it also for employer

and you know what? I've done it before already and been the happy guy in the office laughing at all the trouble people forced to use macs had

EDIT: ofc if I'd know beforehand that mac is the only option I simply wouldn't apply to that place, there's no reason to make your own work lower quality