I would invert the title a bit:
The quality of your life strongly depends on how many bad people you manage to avoid.
People are mostly OK and reasonable to deal with. Some super duper partner will not increase quality of your life 10 times. There is still work, kids and so on.
But bad partner or friend can easily make your life 10x worse, or even put you in jail.
> there are Diminishers and there are Illuminators.
Self-help bs. Normal people are too busy with their lives and paying bills , and will not do some monkey dance to "illuminate" your path.