[cschneid]

There are two ways to get bitcoins from mining.

The block reward, which halves every once in a while, eventually hitting 0 after all are mined

And then the transaction fees. Basically if I want to send a BTC to somebody, I send the coin to them, and also sign over a small extra amount as a transaction fee. A miner who solves a block (ie, a bundle of transactions) can send those fees anywhere they like (their own account).

So in a long-run situation, mining effort will balance out transaction fees to come to some sort of equilibrium.