You may clear some profits by retirement age...depending on when that is...age 65 or 72 but so long as you have the time, lower prices are just discounted buying opportunities. :-))
When the '08 bust hit one friend said of his 401...hell, I'm buying, this chit is costing me half of what I was paying for it just a short while ago. Where else can you get a deal like that. A long term thinker was he.