The other reality is that there is no “ultimate weapon”. But if the Russians or Chinese were to send a bunched-up tank battalion to attack a Marine beachhead or a Ranger battalion guarding an airhead, then the USAF, Navy or Marines are definitely willing to trade a pair of F-18’s to stop those 50 tanks.
Now if the near-peer opponent sees that US capability they aren’t likely to use mass armored attacks against US troops and then those Marines & Rangers can defend themselves pretty well with Javelins and TOW’s against dispersed enemy armor.
Erm... the assumption that infantry can defend itself easily with man portable ATGM isn’t really all that valid any more. As has been demonstrated in Syria and Chechnya as well as Lebanon, you now need to saturation attack an APS equipped tank to get a hit. The Chechens found that they had to fire at least six heavy ATGM to have any chance of getting even one hit. The Israelis with their APS equipped Merkavas found that it took even more RPGs to get past the APS.