The point is that if transactions are not scarce, fees will be low, and without tail emission (of which bitcoin is proud), these fees are the only thing that will pay for ledger security. The ledger is ONLY be secure because it is too expensive to do it over, that is, in order to do it over, one has to spend more than what is potentially at stake (double spends).
As such, the block benefit (reward + fees) must not be significantly smaller (orders of magnitude) than the largest individual transactions it contains ; otherwise, it is beneficial for the emitter of that transaction to redo the chain, orphan the block in which the transaction took place, and double spend it to another of his addresses.
For instance, suppose that you do a 1000 btc transaction in block X. Suppose that the total reward per bloc is about 5 btc. That means that mining will not cost more than about 5 btc per block in proof of work, or miners would lose money mining. If you wait for 10 blocks, your counter party thinks that the transaction is safe. You obtain what you wanted from your counter party.
Next, you pay miners 200 btc to redo the last 10 blocks, and insert another transaction of your 1000 btc (to one of your addresses). For miners, this is profitable: they discard 50 btc of bloc reward and the hash rate they spend on it by redoing the chain, but you pay them 200 btc.
Bitcoin will survive only if the price goes to the moon.
There are ways, but not with PoW.
Note that the price of bitcoin doesn't really matter in this story.