Post '08' people had the luxury to analyze for "cheap" vs the pre-'08' pricing and feel a sense of security in there current price acquisitions. 

After COVID applicants were having to submit 10-15 applications on average in my market to secure a rental meaning they might pay a whole months rent or more in application fees!

If My father and I use the heloc to fund the repairs; I'm concerned to have payments on a heloc as well as giving up all the cash flow for a period of time.

Slightly larger rent payment? 

Then Joe sends a letter to Bob and says I bought your mortgage make payments to me.

but, it's not going to be "profitable" for several years, depending on how you define profit.you'll have a down payment, then closing costs - which new investors always seem to be shocked by - then potentially some costs to get a property rent ready, then you'll pay a month's rent to get it listed and rented out, then you'll likely have some repairs after the tenant moves in.  

US population growth slows and fewer new households form, which is probably not great for RE investors; and 2. the Social Security trust fund runs out.  

Also, added smart-deadbolt locks to each bedroom for extra security in house-hack situation.What was the outcome?

Are you using a 20-35% down payment when evaluating point 3? 

After a few candid conversations, they realized they could negotiate slightly higher rents by offering small improvments..things like better loading dock access or upgrading the security features..turning a so-so cash flow into something much healthier.When you break down your family friend’s situation, it might help to consider these angles:Selling and redeploying capitla could open up opportunities in markets where cash flow is a bit juicier.