This feedback loop finds no end

Of course there is an end. In your scenario all the HBD gets converted and that increases HIVE supply by 10% (or only 1% in the hypothetical alternative which you claimed makes no difference, but of course it would).

For the cycle to repeat, the price has to stabilize or increase substantially enough (which absorbs at least some of the inflation as deflation) to rebuild the HBD supply and then start going down again for some reason. The reason for it to go down again is people not seeing value in the blockchain.

I believe the size of the pie will grow massively long term

You're entitled to believe what you like, but I don't believe the pie will grow massively from the failed social platform. We need to build additional value to the platform which includes a stable value component IMO.

without additional leverage, and I don't want to trade faster gains for more blow up risk.

The leverage is minimal and the blow up risk is entirely nonexistent because of the cap. What you're describing with repeated declines is not a "blow up" at all, it is just a small amplification of what would already be a catastrophic decline anyway.

The 99% decline was simply because the extreme speculative demand driving the price to $10 or whatever it was during a brief crypto boom based on thin air and went away, and was replaced by nothing (Steemit essentially abandoning the project and treating it as a naked cash grab, which happened long before the sale to Tron, for sure didn't help). The decline would be very similar (and was similar for many other cryptos, many of which didn't survive at all) without SBD/HBD.