At most I can get +5 from wisdom assuming I neglect 2 of str, dex, con. I still need a 14+ to pass vs a high level wizard and it took a ton of ASI's to get to that point. For that much investment the benefit isn't enough.
Str 15 (16), Con 13 (14), Dex 10 (11), Int 11 (12), Wis 13 (14), Cha 11 (12) = 27 points.
2 x ASI (Strength). 1 x ASI in Int and Cha and 2 x ASI in Con.
Str 20, Con 18, Dex 11, Int 14, Wis 14, Cha 14.
Saves @ 20th = Str +11, Dex +0, Con +10, Int, Wis and Cha +2 (3 x re-rolls per day)
He gets 2 more ASI's than most other characters. at most he can have +2 more stat bonus to a single stat than any other PC in the game. That's really what you are suggesting make him good at saves? That's laughable.
Those ASI (plus indomitable) help his saves.
Oh great point. Even if I shore up wisdom, my int or cha saves will be in the nearly 20 to pass boat....
The above stat line needs a 17+ to pass a Charisma, Wisdom or Int save (DC 19). A 20 percent chance per roll, with 3 x re-rolls allowed, and a further save allowed every singe round from there after (also with re-rolls).
Do you play with Clerics, Paladins or Bards?
If so, hanging out near the Paladin gets you +1-5 to saves. An active
Bless spell grants you +1d4 to all saves. Bardic inspiration will get you +1d[6-12] to a save.
Warding bond adds another +1 to saves (and gives you resistance to damage).
Anything that sticks can be removed with a
restoration spell (lesser or greater) or
dispel magic or
calm emotions.
This is a team game remember; you're not supposed to be good at all saves and be a damage powerhouse. Monks are proficient in all saves (with a re-roll) at 14th but they dont come near the at will damage you deal. Strengths come with weaknesses.
If you're deeply worried about Saves, dip 2 levels in War Wizard. Gain an at will +4 to a Saving throw as a reaction.