If light can behave like a particle, doesn't this mean matter can travel at the speed of light?

Could you also please answer why can particles be accelerated to 99.9999999999(...)% the speed of light but can never reach it? The speed of light has a numerical value, and in math there's always +1, so can't we just give those particles a +1 "nudge" and accelerate them a bit faster? Why can't we?