So, there's two seperate questions that could be answered here.
Can you fight unarmed, using primarily punches, and wear boxing gloves? Absolutely. In fact, Unarmed is among the stronger combat specializations in the game, though Boxing Gloves are somewhat weak specifically, because they cause only subdual damage - meaning they will knock your opponent over, but not kill them. Useful sometimes, but rarely.
Can you fight in a 'boxing match'? Well, not per se, however, there are two opportunities for you to engage in a sporting fight for some caps. The Thorn in westside is home to one such opportunity, where you'll have the opportunity to fight off various monsters of the Wasteland such as Radscorpions, Giant Mantises, Deathclaws and Cazadors. Any weapon is fair game in the Thorn, though you're welcome to go in unarmed if you're looking for a challenge.
Male (and only male, the legion are nothing if not chauvinistic) Players aligned with Caesar's Legion meanwhile, have the option to fight in The Arena, located at The Fort. In the Arena, the only weapons permitted are Machete's. All your other weapons are confiscated at the beginning of a match, and you are of course free to use your bare hands instead if you so desire.
Charisma increases your speech and barter score, and if your charisma is too low some interactions will not be available, regardless of your speech or barter skills. According to the wiki though, these interactions ultimately do not have any significant effect on game play, nor do they provide any special bonuses.
High charisma is also required to obtain the Ferocious Loyalty and Animal Friend perks. Ferocious Loyalty grants your companions a boost to damage resistance when you drop below 50% health, and Animal Friend will prevent animals from attacking you unless you attack them first. Something to note about Animal Friend however is this:
Deathclaws are not classified as animals for the purposes of this
perk. Neither are any variety of arthropods such as radscorpions.
One final thing to mention is that it also increases companion nerve. Description according to the fallout wiki:
Companion Nerve gives each companion in the party +5% to their damage
and armor, up to a maximum of +50% at 10 Charisma.
Best Answer
It's not wasting points.
100 stealth will get you much closer than reasonable sniping distance. However, there are quite a few enclosed areas in which you'll have to get a lot closer than normal sniping distances just to be able to see your targets (inside vaults, for example), and higher stealth will definitely help you there.
Furthermore, the number of points a high-intelligence character will receive by hitting the level cap is enough to max out almost every skill. There are actually a lot more skill points available than there are skills worth maxing; maxing sneak is hardly a waste of points, compared to, say, maxing survival in a non-hardcore playthrough.