Underground lair.
Yes, it sounds odd, but that is the first thing I thought of when I saw the proposition.
Lanai is a volcanic island. There must be caves.
Caverns deep and mysterious from whence I can plot my plots and think my thoughts… of world domination.
An X-men type academy for brilliant children and their families.
Build a pati’o on Lana’i. 
OK. I can see that.
You may rent one of my caverns at a discount rate.
Have your people call my people to work out the details.
Will that be “Doctor TruCelt’s School for Exemplars”?
I would start an Esperanto-speaking mini state. This time, it would work. It would have beaches and tropical goodness and a thriving tourist industry. True, the fine print would say, “Lana’i County, Hawaii, USA, d/b/a the Republic of Esperantia”, but that’s only until we [del]get the solar weapons working[/del] negotiate a peaceful secession.
Is there a volcano where I can build my base?
Oh, I’m in.
Do you know how to build a solar weapon?
Yeppers.
According to Wikipedia (so it has to be true), Four Seasons Resorts owns two resort hotels there, and Four Seasons is 47.5% owned by Bill Gates. So maybe he just wants to be Bill Gates’s landlord.
Refurb and flip for profit.
I think you meant: “Ho, mi in.”
^This!
Or else plant Hawaii’s other profitable crop. And I don’t mean pineapples.