Enlist because you want to. There are no guarantees in life. If you enlist just because you want a pilot slot and don't get one how will you feel about your enlistment?
If it's a local unit and the enlistment lasts as long as you are in college, and you're interested in the enlisted job, it can be a very good deal/plan.
Many units don't require prior enlistment. Does enlisting slow down your overall goals? Does your current plan make you a competitive candidate for other units? If no will you be the most competitive candidate at your local unit?
Being enlisted in a unit can be a big plus. Prior enlisted service is also an overall plus at other units. But that's just part of the puzzle. My old unit picks the best candidate, to include out of state with no prior service, vs candidates they don't select that may be in state and have prior service. They've done very well with the candidates they've chosen.