The difference is percentages. I am highly confident that if we looked at a large number of high-growth startups and then at the top ~10 paying tech companies and compared the work/life balance, the disparity would be abundantly clear. In other words, you are much more likely to have good work/life balance at a large tech company than at a high-growth startup. Individual examples to the contrary will obviously exist on both sides, but don't negate the reality of what the average employee is likely to see.