Tell me if B is in this location( New York City best zip code ),

https://www.zillow.com/homes/for_sale/Great-Neck-NY-11021/31067578_zpid/61983_rid/4-_beds/300101-_price/1106-_mp/globalrelevanceex_sort/40.800085,-73.703757,40.771165,-73.749891_rect/14_zm/

what is B's investment return? It is likely $0:) 

Or you can pick any place in Florida:)

And now in many zip codes in US, high end house price is already going down like the above. Anybody who take your advise using heloc to buy high end houses may lose their heloc in the coming years. This chance is high. The reason is the following:

Higher income middle class is disappearing just like Macy is becoming JC Penny. If US continue this route, high end houses will have no buyers:)

B might be just a lucky bustard:)