Why sexual reproduction in plant waste energy and pollen

Sexual reproduction in plant waste energy and pollen grains because the size of pollen grains is very small and in sexual reproduction there is less chances of reaching the pollen grains to the stigma of the flower. So that's why more pollen grains will fall on the stigma of the flower in order to fertilize the ovary. For fertilization, few pollen grains are enough if reach on the stigma.

i'm pretty sure it's spores