Johnzx,
If its not the banks money and is as you say the Investors, why aren't all the profits returned to the Investors, If you buy shares your liability is capped at the amount you Invest and the shares you buy. If the company subsequently goes bust the shareholders lose their Investment they aren't liable for any additional losses not covered by by the assets of the business its called Limited Liability.
Why should a Bank be able to secure a loan and then if the asset doesn't covered the outstanding liability be able to pursue beyond the asset, its a ridiculous scenario that has encouraged banks to lend at levels they shouldn't have agreed, overvaluing houses to increase profits via larger interest payments safe in the knowledge if the debtor can't pay they can add costs additional interest and still chase the debtor till their dying day.
Theres's not an Investment in the world that's completely risk free so why should the Banks expect the debtor to carry all the risk, if the market fluctuates surely the bank should carry some of the risk therefore only be able to reclaim the ASSET IT SECURED THE DEBT AGAINST!.
You need to bear in mind its the Bank that values the asset not the debtor, also before anyone points out what happens if the property increases in value only the debtor benefits simply isn't true, as this then presents the Banks with a further opportunity to lend again to the next purchaser with a larger loan and therefore incresed costs and Interests.
If the bank loses money blame those managing the business as we would in any other walk of life not the customer.
If the bank secures a loan to any commercial entity it secures against assets and can't go beyond those assets if the business fails, so why one rule for one, a different rule for others!