You know, God is probably asking that same question. Why don't people worship him?
Consider. Worshipping God is a thing that He demands. But worship isn't something that He needs. Since He doesn't need it, why does He demand it? He demands it because, what we are makes God-worship a requirement. If we don't worship, we will be destroyed... not because God needs it, but because we need it.
Why do we need the worshipping of God? For our salvation. We sinned in our first parents, and lost the perfect image of God. Because of this, our destruction is naturally imminent, except that God through Jesus payed the ultimate price to save us. We still have freedom to reject, like our first parents. But we have the chance to be made alive again, but it's only through God.
If you lose an arm or a leg and can grow it back again, maybe you don't need God. Maybe you can keep yourself alive forever. But if you can't, your death is imminent, and there is only one thing that can save you... God. What's more, even if you find the right drugs and nutrients to stimulate yourself into never dying, you will never be strong enough to stop the coming destruction of the universe, and you will be destroyed in that.
It's like a painting. Imagine that you find a work of art that touches your soul when you see it. It is so good (for you at least) that it resonates with your soul. You can't help it that your eyes light up, and that you feel the resonation, and that you proclaim the beauty, and maybe you even praise its creator. It just happens. You aren't trying to be affected. You simply are.
It's the same kind of thing with worshipping God... except for the little detail that worshipping God is the thing that keeps your whole life alive forever.