1: It depends. I'd say you have to be good enough to know how the shot is supposed to turn out; if you are, you'll see discrepancies when you compare different balls on similar shots. If you really know how the shot is expected to turn out, you're probably playing decent golf.
If you hit 100$ worth of brand new balls in the woods every round, that's your problem. Most Titleist balls are played by posers anyway. If you want to hand them money it means I will find more free balls on the course that are good quality. I'd rather get a free ProV1X than a crusty old Nike Crush. Plus you'll be able to play less often so the course will be wide open which suits me fine. A scratch player will want a ball with a urethane cover that performs off the long clubs and irons well, but it's not as though he'll be transformed into a 30 handicap if he doesn't have the top of the line ball. They're a luxury.
2: The X spins less and is slightly longer much like every other company with 2 tour level balls. The company says they work great for everyone but they're not designed with amateurs in mind. They're built to win on tour so they fit tour players' games. That means an average of 112mph driver swing speed, averaging 290 yards per drive, 7i distance in the 170s and scores in the 60s at most courses. If you fit in well with those kinds of guys, go for it.
3: Tour players don't have to pay 48$ a dozen and if they did they could afford it. They are copycats and many don't like to change brands, and Titleist also has equipment deals with many players that include apparel, clubs, etc. Without the consideration of price, they're still one of the best balls and they fit a lot of players. Personally I think they're two of the top 5 balls in the short game but they aren't better than some cheaper balls overall, and they aren't that great off the long clubs for me. I prefer the X. But if I buy them I feel I should have bought a different tour ball and kept 8 dollars in my pocket.
I find older urethane balls on sale and stock up. I just got 4 dozen 2013 Nike 20XIX which I like a lot for under 100$, easily enough for 15-20 rounds. I played a lot of bridgestone E5's last year and had some of my best golf. Of course, if you use the search function, you'll see a lot of similar threads in which this question is beaten like the proverbial dead horse.