I once knew a man who meditated for two hours every day over thirty years. I asked him what he had achieved. "Nothing - it was a complete success. "- he replied.
Meditation isn't a wholly futile activity, but to do it with the expectation of turning your miserable, meaningless life into a perfect rose garden is delusional. It has been said by many zen teachers (real ones, not the ones selling you images of a perfectly calm life) that to meditate to achieve something is just a waste of your time - although it has to be said that time was invented to be wasted. In any case, the promises of bliss and endless joy are just snake oil, and we shouldn't forget that this is big business with millions of people willing to spend large amounts of their hard-earned money to realize the claims of the snake oil salesmen. If you want to meditate, do it because you like it, and not because you feel you have some divine duty to fulfill, or because you expect to be delivered from your misery. If you can meditate for two hours a day over thirty years and achieve absolutely nothing, you can be assured that your practice has been of the highest possible quality a human being can attain. Anything else is just second rate, and the time might have been spent more wisely watching 1950's sci-fi movies.
“although it has to be said that time was invented to be wasted”
I like. Wasting time helps in guarding against spiritual materialism.