I only needed 75 points myself, but a resale came by that was too good to pass up. Buying more points than you need for your use now, if the price is right, makes a lot of sense to me.
It isn't an 'investment' strategy to rent out points in this way...it is just good business sense. i believe that with ROFR and the Disney name, that for at least 10 years, the resale of your purchase will either stay the same or go up enough to recapture initial purchase price.
Renting at a low of $10.00 per point, gives you 'double your money' insofar as maintenance point costs...so renting half pays the maintenance (and a wee bit more) of the half you use. After the initial investment...you are getting your vacation 'free'. And then as another poster said, down the road you might find that you prefer to use all the points.
My strategy seems to be very much like yours. I investigated the rental price that Disney 'rents'
DVC for, and even at it's best promotion code...it is still twice what $10 a point comes out to. So I think you are protected there, especially since we arent' talking a kazillion points...you could rent out easily 100 points with one reservation.....a couple phone calls, a standard contract and Paypal and you are done.
I think some of the responses come from people who can't imagine not using all their points to gratify the Disney addiction. I think more along the lines of having my cake and renting it too!
I am a new member, making my first visit in May. I never impulse buy...I read these boards religiously and applied my own investment theory to the purchase. I think your thinking is right on target. Good luck!