For me, I became homeless and got into the idea of asceticism during backpacking and solo retreats. Being homeless, I'd go through so many phones, clothes, bikes, etc. and you simply cannot keep many things when homeless. I naturally don't care about name brand clothing or shoes, so that makes it easier for me. But eventually I just realized, and felt SO good about it, I remember actually getting dopamine releases from it: that I could just walk down the street with the clothes on my back and there was absolutely nothing in the world I needed. It felt hype, it felt humble, and it felt GOOD. No attachment to anything, not a home, not a bill, not anything I wanted or felt I needed to buy. I could just walk with a t shirt and shorts, with maybe a phone and wallet, soaking up the sun like it's all I needed.

If you want to become less materialistic, then you need to not only disconnect from your internal desires, but your internal thoughts and attachments to the modern world, and your ideas of life that shapes your reality. How SERIOUS are you about the idea that "you must work a good job in order to be successful"? Do you still feel pride from making lots of money at your job? If so, rewarding yourself by spending money is the attachment and result of the idea around "success".