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What makes you say that? Only if one is speculating, not investing, do you want to get "in and out"...that's not to say one never rebalances a portfolio, but it's the penchant for day trading, etc., that typically leads to poorer returns for most than an informed buy-and-hold strategy over the long term.
Foregoing the thought of hitting the big winner for long term gains will end up w/ comfortable returns if not spectacular during bull markets and far reduced losses during bear periods. Again, we're talking long-term (30-40 years) retirement here, not short term speculation.
I'd wager if one simply used any of the broader market index funds balanced w/ some bond funds starting at age 25 w/ regular contributions there will be little likelihood of not being comfortable at age 65 (or well before). In essence, that's what I'd like to see done...an enforced conservative savings plan for all since it appears the bulk of the young these days are more into self-gratification for the moment than thinking of how they're going to get by later on...ideally, it wouldn't have to be forced, but that's better than the alternative of continuing the "pay-as-you (hope) go" plan of the present.
Something similar for med insurance will also need to be done eventually.