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Currently the fees are very, very, very far from being anywhere near of an amount sufficient to secure the network.
We're all having a free lunch right now, due to coins still being minted, ...
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Yeah, and when block reward shrinks enough that miners start getting squeezed, they'll stop including transactions with fees that are too small for the transaction-inclusion to be profitable to the miner.
This is how it would play out if the blocksize had no limit at all. There'd be a genuine free-market for block space. Denial-of-service and propagation-time concerns are at least worth discussing, but the economic argument against the blocksize increase is silly.
https://bitcoinism.liberty.me/2015/01/21/economic-fallacies-and-the-block-size-limit-part-1-scarcity/