Earlier quoted context omitted.
Bitcoin's security does not need to keep going up indefinitely. It will reach an equilibrium where tx fees will be paying for the entire security of the network. As the block size is capped, there will be a market for fees. Hard-forking to remove the block size limit would have profound consequences for the decentralized nature of bitcoin - arguably its most important characteristic.
Assume a block size limit of 4MB. The minimum transaction size is 166 bytes. This gives us maximum 25266 transactions/block. The current block reward is 6.25 https://blockchair.com/tools/halving-countdown This is worth about $72,000 USD https://duckduckgo.com/?q=6.250+BTC+to+usd&t=canonical&ia=cu... This means that, to match current security without block rewards, transaction fees would need to rise by at least $2.84…
Needing to roughly double the status quo transaction fees to make up for lack of the block reward in order to provide equivalent security, doesn't seem ridiculous to me at all. And this is the worst case scenario (i.e. the reward will go from 6.25 to 0 slowly, but it can't go negative).