So, to paraphrase, the problem is:
"I have a player who gets upset when he doesn't do as much damage as the other players, but he wants to do so without putting in any effort, and while in an environment that is being made hostile by the other players, in a game where nothing except combat matters and resources are never taxed."
And from the sounds of things, effort includes:
Multiclassing, dual wielding, taking feats, abusing opportunity attacks, coming up with cunning plans etc.
The base rogue class does a couple of things extremely well:
1. They don't expend resources, so if your adventuring days are so short that (say) the barbarian can always be raging, or the sorcerer never needs to conserve spell slots, then they are not going to keep up.
2. They do skill checks. The rogue is going to need to put some effort into lining up skill checks that will swing combats, and the DM is going to need to let that sort of thing happen. "I throw a dagger for... 17 points of damage. Then I use my bonus action on an automatic success on a DC 20 disable device check to collapse the roof of the tunnel, burying most of the enemy force" is the sort of thing that is possible for a rogue, but ineffective for anyone else (most classes would get a 50/50 shot at the skill check at best, and need to spend a full action for each attempt).
I would advise NOT hiding in the middle of combat BTW. Rogues only have slightly fewer hit points than a fighter, and only slightly less AC than one clad in full plate. They then halve the damage on one attack per round and often take reduced damage from spells. They should be far from squishy. Although my guess is that your rogue has done something silly like dump constitution and then wonder why he has so few hit points.