I don’t think it’s about having an edge over others, but about Bitcoin itself and their own piece of the pie ofc. We also don’t know what effect tail emissions would have on potential late adopters, as there will be many competing assets without it, and having some sort of inflation mechanism could make Bitcoin less competitive. Leading to less adoption again and then potentially devaluing the amount miners would have earned too. We can’t assume Bitcoin will have won it all already. The value proposition Bitcoin offers now, will be huge even to late adopters, if we compare it to other assets.

Also the security budget is important, but we don’t know if the absolute amount is the only relevant metric to consider yet. The access to attractive locations and the distribution of mining should be considered too. There is places with close to 0 electricity costs, and as Bitcoin rises in adoption and the potential price increases become less. Mining might become so competitive(barely profitable) that it could just be possible for a few big players anyways, and be almost exclusive to locations like this. Which will also make attacks from the outside harder again, without access to these locations. Or even make it hard for new miners to join, as it will be hard to get access to locations like this. A tail emission also doesn’t change how mining will be distributed as it becomes more and more competitive.