I think that is probably true for a lot of people, that they get as "much" boat as they can - it certainly seems to be true for cars, houses, and whatever else people buy. Many people do grow out of that eventually, however.
I wanted to add something to this.
I think that a reasonable person will eventually get to the point where they see a boat in terms of its suitability for its purpose and choose a sensible boat even though they could afford "more". Many things in this world are just fine the way they are, a spoon for example, it could be bigger, have a longer handle, be more ornate, made out of gold, or whatever, but you know, adding all that stuff to a spoon doesn't make it a better spoon, it has been adapted over a long period of time by many generations of people to be what it is - just the right size, shape, length, weight, made out of the right materials, with the right surface finish, etc, to be good for what it is used for, eating. There's really just not much you can do to a spoon to make it a better spoon, it is perfectly suited to the needs of the human beings who use it. I think at some point people start to see boats in the same way, yes, you can buy a much bigger boat, you can load it up with all kinds of junk, base it on all kinds of exotic designs, etc, but in the end there is a boat out there for most people that just fits, and it probably isn't the biggest one. Human beings average a certain size, can lift a certain amount, handle sails of a certain size, move at a certain average speed, can be expected to deal with a certain amount of complexity, etc, and when you look at it as a whole certain boats just make good sense, good sensible sense.