"The career/job" doesn't really fit, unless you were talking about a specific career before saying this and are trying to refer to that specific career. You can say: "One's career...a social life..." - I think this is the most natural. "One's career...one's social life..." "A career provides one more...than a social life..." "Careers...social lives do ". "A career...one's social life..." doesn't sound very natural to me. The following sound natural to me: "...one's job...their happiness...their/a social life (does)." "...a job...one's/a person's happiness...their/a social life (does)." "...jobs...people's happiness...their social lives (do)." I recommend you change "more effects" to "a greater effect". In all instances, 'do/does' can be omitted and would be in casual conversation. In writing, it sounds 'smarter' if you add it. I also think "one" sounds unnatural outside of formal contexts, but apparently it's extremely common in the UK. If you want to talk about a specific person or group of people, I think you should say "I believe their jobs have...their happiness...their social lives."

I personally think you just need to add "A" before Career and Job "A" Career provides more happiness in life than one's social life I believe "A" job has more effect on one's happiness than a social life. But in the flow of this particular sentence, you want to keep using the same pronoun "One's". ONE's Career provides more happiness than ONE"S social life