There will be interest on the loan. Probably fairly low given the collateral, but it won't be 0 (assuming this is not a sweetner from some investment bank that

There will be interest on the loan. Probably fairly low given the collateral, but it won't be 0 (assuming this is not a sweetner from some investment bank that works a lot with Tesla/SpaceX). If it's hedged you actually don't have any upside so you will always be 'underwater' on the loan assuming >0 interest rate. If interest rates were higher, it probably wouldn't make sense to do this endless loan trick[1]. Say you get charged 5% on this loan or you could pay 30% cap gains. It would only take 5 years for the interest payments to outstrip the upfront hit on the tax. 1. This is very simplistic though, as likely the $1bn would be invested in some way that would kick off some return, probably enough to cover the interest.