And BT earns upwards of 100 Hive in curation rewards for every one of those auto-votes.

I vote for the stabilizer because these funds ultimately go to the DHF so that the chain can build up enough of a war chest to support more development. I believe the future of Hive depends on increasing the amount of development that is done, and the blocktrades development team, as strong as it is, can only contribute so much.

As @smooth has pointed out, I make the same curation rewards regardless of which posts I vote for (as long as those posts aren't actively downvoted, of course). If you check my curation rewards on something like hivestats.io, you'll actually find that my curation rewards tend to be a little lower than the optimal return. I haven't really bothered to analyze why.

You're trying to argue that voting this way somehow builds (or at least maintains) my percentage of the stake, but that's not how it works: my stake erodes via the inflation regardless of whether it goes to the DHF account or to any other account. This is basic math. If you believe you can demonstrate otherwise, please show your work.

TLDR; I vote this way not to maximize my personal stake percentage (this doesn't do that), but because I believe it is the most beneficial thing for the long term viability of the network right now. It doesn't take a lot of effort to see that it is the work being done by devs that is bringing new users to the network.