While I can agree with much of what you say (the mugging for the camera, etc), but things like going to the ground at the end of the race is something I can completely understand. I ran in the New York City Marathon in 1992 at age 30. At the end of it I thought I was gonna' die. Yeah, I fell to the ground, but it was just because I physically could no longer stand.
As for training, it's no different than training for anything else. You commit yourself to something and you do what you have to do in order to attain the things you need to do it. For a serious triathlete, $10,000 isn't expensive, at all. Think about it: If you're a mechanic, are you going to want a set of quality tools like Kobalt or Craftsman, or are you going to settle for the garbage you can buy down at Harbor Freight's parking lot sale?
In everything I have ever done, and when I give advice to others, it's always "buy the best you can afford".
I'm an avid photographer; have been since the 70's. Through the years, I've made countless equipment upgrades, eventually moving into digital. My last camera purchase was a Canon 1DX MKIII, which is $6,500 from B&H in New York. It's the top of the heap in Canon's offerings. I could afford it, so I bought it. I may not avail myself of all of its features now, but I might a year from now, or two years from now. The point is that when I want those features I won't have to buy another camera.
It's no different with bikes. Someone training to run a triathlon four years from now may not need to have a bike frame constructed of carbon fiber right now. But that's something he'll want when he runs that race so, if he can afford it now, why no buy it now?
Shoes for $300? Meh. I watched a buddy of mine in Calgary once drop $450 on a pair of jeans. My hot Puerto Rican girlfriend has a $600 Coach purse. It is what it is. People will see something they want and they'll save their money until they can buy it. It's not a new concept.
Lastly, most Olympic swimmers train at either universities or Olympic Training sites
like this one in Chula Vista, California...