For the doubting soul there is happiness neither in this life nor the next.
Don't let the fact that there are no permanent solutions in the material world paralyze you from acting. Seeking perfection in material life can be crippling. You can be so attached to having a certain situation that you cripple yourself.
Change is happening constantly. So to be averse to or attached to any one circumstance is to eventually be bitter that the circumstance changed.
But does that mean you take life lightly? Does it mean that you don't invest your heart and soul in projects that you work on? I think it takes maturity to strike that balance. It takes maturity to do your best in a detached fashion.
For some people, unless they pour their heart and soul in something, they feel like they are cheating themselves and others. Maybe for these people detachment is about taking life more lightly. Maybe its realizing that there isn't anything worth killing yourself over. That everything, good and bad, changes anyway.