The security budget is total fiat denominated miner reward of the entire network. The higher it is, the the more resistant bitcoin becomes to 51% attacks.
As you know, each halfing decreases the block reward, which is currently the largest part of the total miner reward. In order keep a steady security budget, the price and market cap has to double each time as well. But remember, the security budget stays constant, so an ever increasing amount is secured by a relatively lower share.
Transaction fees make up the remaining tiny share, and I honestly don’t see it growing much. Because the higher this fee becomes, the more people will find ways to avoid it, and just keep it on exchanges, custodial solution or lightning. This reduces the decentralization , the primary feature of bitcoin, and thereby reduces it value proposition.
All this can be side-stepped by having holders pay a small, program-ably guaranteed fee proportional to their holdings, which is then paid out to miners. Yes, this is similar to inflation, but as long as it is lower than fiat inflation I can be worth the trade off. Considering how cult like bitcoin holder are, I don’t think this is a change they are willing to make, at least not before it’s too late.