I have acquired a fair amount of gear over the years and have probably spent more money than most. But, I don't really have other hobbies that I spend money on. No kids at home. And, it is what I like to spend my time doing. Probably one of the biggest reasons I tend to just buy stuff is I am simply not at all a "do-it-your-selfer." It is not that I probably couldn't make things, build a brew system, etc...... I just don't want to. Can't stand spending my time making things or putting stuff together.
I think you also have to look a little at cost vs. use. I bought a 3 tier gravity brew sculpture from More Beer 17(ish) years ago. Lot of money at the time.... $1300 or so. But, I am sure I have brewed 400-500 batches of beer on it - so, I can easily say it is the best money I ever spent. 1000's of hours of entertainment over a couple decades is simply something I am fine spending money on. Same with other things I have spent money on like temperature control, kegerators, etc. I love brewing beer and I love entertaining friends that come over to enjoy it. Money well spent.
That said - do you NEED to spend money on shiny equipment to brew great beer? Absolutely not. There are tons of people who brew spectacular beer on modest set ups - as evidenced by many of the previous responses from some truly great brewers. Brewing good beer is about process, learning and practice. No equipment will help a person brew good beer if they don't have those things.
There are a lot of home brewers who really enjoy DIY and tinkering with development of new ideas, improvig old ideas, repurposing, and doing things on the cheap. New, techy, shiny, and expensive gets kind of poo pooed, a little at least. I have a little money in my setup, but its nothing to show off. I'd love to have a big new digital pid setup and I might some day.
The cost issue kind of cracks me up though. Cost in hobbies is relative to the culture of that hobby. If I piled up everything I have aquired for brewing, maybe $3k new. I'll bet there are plenty of brewers on this forum whose pile would be $300. And some whose pile would be $10k. The majority reaction to $10k tied up in brewing would probably be "Holy cow! You must be filthy rich!"
How many garages across America have $10k worth of brewing equipment in them? Maybe 50? Maybe 500? A safe bet would be less than 5000.
How many garages across America have a $10,000 Harley in them? A safe guess would be that 100,000 garages are home to a harley that hasn't been riden in over six months. No one blinks an eye at the idea of pouring $10k into a harley. Mine was $25k.
My farmer neighbor bought an airplane this year. He was over having a beer with me and sheepishly spilled the beans that he spent $52k on it. His friends all think he's nuts. He flies every day off. I told him that maybe he should have bought a $50k class A RV, then everyone would snicker at what a cheap ass he was, cuz their class A cost $150k.
My harley cost $25k. I rode it three times this year. My RV cost $14k. We camped in it 8 nights this year.
I have $3k max tied up in brewing stuff and I used it a minimum of 24 full days this year, not counting a few random hours each week.
Brewing is the cheapest hobby I've ever had, per hour enjoyment.
Brewing is a hobby, therefore a luxury, but I think its cool that a lot of us consider cobbled together repurposed mishmash, a luxury. I also think its cool that some of us consider a $350 peice of stainless a necessity!