Can't argue with your logic: don't use it ==> get rid of it.
However, if you are looking for reasons to keep it, they are, roughly in order:
1. They WILL be severely restricted, as to ownership, but likely with a grandfather clause, at the federal level, within 10-20 years, due to Florida, Texas and other places turning blue (i.e. anti-civil-rights), thus swinging the national pendulum back to tyranny ...thus the upshot is they will increase in value, so they are a true investment of sorts. [Note that to the extent that one can predict whether or not a grandfather clause will be present when the ban(s) come, it would be important to so attempt to predict, because: (a) if there is no GF clause, then these are terrible investments as they will be worth nothing, but (b) if there IS a GF clause, the polar opposite end of the spectrum applies, as to value - they will greatly increase in value. Also note that the most recent ban at the state level - Florida - following gun-hating hysteria did NOT contain any GF clause as to that ban on bump fire stocks and binary triggers - meaning not only are instant felons created, these are worth much much less, and worth $0 on the legal market *in that state* (maybe they can move them out of state to sell them?) ].
2. Do you have any plans to increase the frequency at which you will take noobs to the range? If so, they are one of the guns newbies will enjoy on about the 3rd range trip (always stick to .22lr only the first trip, and rimfires generally on the 2nd trip, IMO).
3. To bolster the argument that they are "in common use" under Heller, as but one person in the statistical landscape, thus bolstering their constitutional protection argument, thus helping prevent or at least helping to slow down their (likely inevitable) banning?
4. WROL scenario - well, yes, it WILL happen, but the chances of it happening in YOUR lifetime, where YOU live, such that YOU will actually be a firefight where a semi-auto will actually be the difference between life and death, are nearly nil. So this is very weak - essentially a non-reason, but there it is.