Generally speaking, work-life balance is harder to achieve for jobs that have to do with the core functions of a company.
In plain English, there's basically three kinds of jobs within any company in any industry:
Those who sell it, those who make it, and those who support the former two.
If you're in a job that "sells it" or "makes it" -- then the hours are less structured, more demanding, and there's greater expectations that your career be a greater priority than your family/personal life (i.e. more expectations to miss vacations, holidays, major personal events, etc. for work-related things that may be deemed more important for the company).
If you're in a revenue generating role and/or a role where you're building the company's core product or service, there's really not going to be much of a work-life balance. Even if let's say you want to be a partner at a fund -- you may have decent hours when there's not much going on, but if there's a big deal or investment you're making, the other fund partners are expecting that you make that a priority, even if such a deal/investment happens to take up a lot of your time that could coincide with personal/family stuff - of course it's not draconian (i.e. "you must miss your father's funeral!") as there's a bit of give and take in any front office position, but more often than not it's expected that you are to schedule your life around work UNLESS it's something major (i.e. death in the family, getting married, etc.).
That's why it's tough - not impossible, but always a tough trade off people make after a while. And why not everyone wants to move up the ladder after a while (or are willing to take a support/back office job if they really value their personal/family life even more).