Raising bug bounties by an order of magnitude goes a long ways. Apple's program is pretty good relative to industry norms, but all of the programs are well below black/gray market prices for exploits, and most are below costs to find, document, and submit an exploit. Google pays less than a month's salary for their most serious Chrome exploits, for example:

https://bughunters.google.com/about/rules/5745167867576320

I think all this is good until an adversary decides to brick every iDevice, Android, Windows, MacOS, and Linux machine in the US. And by "brick", I mean overwrite firmwares, disable fans, and run at maximum load.