We're not talking about I/Os here. Sure I had plenty of fun behind I/Os growing up and when I got my first boat, which was an I/O. It's not the same, and I'd sooner be riding behind a $2000 ProStar 190 than a brand new "wake" model I/O.
But the choice for an boat is not an I/O for cash of a $30k-$50k inboard on a loan. There are plenty of inboards out there starting at $2000 and particularly around the $5000 range that will be great for slalom/wakeboard/kneeboard. Surfing, there are fewer but they are out there. I rarely surf so I'm no authority of that, but look at WakeMikey's surf setup on an old SunSport. I'm not really into surfing but it sure seems he's got a great setup out of an older cheaper boat that I'm sure is paid for.
If you want new and you don't mind spending the money then great. There's still a easily affordable with cash option for those same activities. I have just as much fun on my old paid for Saltare as I do when I go out on Malibus, Mastercrafts, and other new high dollar boats. I don't just "put around" either, I drop in 1/4 mile from where I ride, and typically ride the whole time the boat is in the water.