Yeah, uh, don't listen to this guy. He just found out about Bitcoin very recently, claims to have read most of the forum, and has made a decision that Bitcoin is a scam, which he is so convinced of that he refuses to even consider any conflicting evidence. That, plus he is convinced that he is a super genius who is much smarter than you, so anything you say to him is automatically stupid and wrong.
If you want to read the definitive authoritative explanation is scalability, by the developers who actually know what's what, read this
https://en.bitcoin.it/wiki/ScalabilityAs for the block size and transaction costs, those will be allowed to float, and will stay low enough to be cheap, but will still be high enough from increased transaction frequency to keep the system secure (instead of 7 transactions a second paying $0.05 each, we'll have 1000 transactions a second paying ¢0.001 each, or something like that). The question of whether transactions will be high enough, or spiral towards zero, was thoroughly discussed over two years ago, and the conclusion was that there are a few ways for miners to compete on transaction costs that keep them above 0, and keep Bitcoin secure.