Leverage reflects the business' ability to attract other loans and investment.
A fully-leveraged business has no further ability to borrow money. Earnings retained in the business will increase both your equity position and your leverage. If it is secured by a debenture or something other than the participation in the profits, then technically it is not equity. Most financiers of commercial debt will insist on a priority claim against assets and force this shareholder to a secondary or subordinated security position. The rewards are direct participation in the profits of that business as well as any appreciation in the perceived value of the shares.