I definitely love the experiment and kudos that you're providing 250 hbd to give out the extra 10%.

As you asked for feedback, I'll explain why I didn't participate as there are a couple of reasons.

1. I don't have that much liquid funds and the ones I have, I prefer to keep them liquid. So locking up funds isn't something I do at this moment.
2. I have all my funds in hive (power) and 2nd layer projects in which I believe. I am rather sure that Hive will atleast reach double of its current value in the next 4 years which would give me a better roi than the 20% of hbd savings. Even with an apr of 30%, I would prefer hive as I am rather sure it would even reach the value of $1 in the coming 4 years. I didn't put 30% in a interest on interest calculator for 4years though. So should check on that.
3. When such a thing as hive bonds would be implemented on the blockchain like hbd apr is (I think?), I would trust it more compared to an individual running it. I know you have quite a reputation on Hive which 99,99999% you won't put at risk, but still.

Want to conclude that I really enjoy the experiment and I am looking forward to the results at the end!