The most important and valuable resource in the world is time. It is limited and non-refundable. You can never take back the time you lost. Time spent productively is valuable. Every second, every minute, every hour dedicated to something that could improve your status whether that is physically, mentally or financially... expect something good to come out of something you made time for.
Actually I agree to the whole thing you have said and that is true. No quality time spent on something that doesn't yeald a good results, except there is something behind it, which could be as a result of spending time doing the wrong thing and hoping to get a positive results. But we can not be %100 sure that all time spent on something must yeald to something because not everyone that benefited from what they spent their time on. But of course time is very precious and when put to effective and positive work and not the other way round.
You have to choose wisely where to spend your time because making this choice, you will be trading an opportunity for another. If you decided to spend this time lounging around instead of dedicating your time to improving yourself then you are losing the chance to be a better version of yourself.
Time is money just as they said, if we do things the right way and be consistent, there will surely be light at the end of the tunnel. I have tested and confirm it. The reason why people spend time and fail sometimes because they either fail to be consistent and patience.