The income from the multi-family would be enough to save, maintain, and modestly supplement my income.

I use my rentals as a way to propel and supplement my passions. 

Also keep in mind that the cost of life insurance is going up every year and eventually premiums that you are paying are not enough to cover the cost of the insurance, at that time funds from your savings component are used to supplement the cost of insurance.

In addition, supplementing my RE education with in person seminars definitely can't hurt (as long as they aren't $300 a pop).

You can also sell on contract, via a wrap note, using a note if you own free and clear, etc.I think the purest form of buy-and-hold investors generally intend to hold the property indefinitely to produce cash to supplement or replace their income.

I'm thinking of investing for cash flow to supplement their monthly income.

I am supplementing this loss with bombing the biggest hills on my bike I can find around here.I almost bought my first property in Hermosa with a former co-worker.

On a few occasions, the deals get supplemental loans (second loans). 

But, those thoughts have entered my mind to have about 20 properties that will supplement retirement.

Start paying yourself a wage from your company, or get a job to supplement (which really is a win-win situation, more money = happier wife PLUS more investment capital).