Just because one opens a margin account does not mean they have to buy using margin. So not sure where your whole "take risk for life" statement came from. All a margin account does is allow you to use funds again before they have settled. Is there risk, yes if you start buying with the banks money. If you are just using your cash in the margin account then by no means is there any more risk involved then with a cash only account

As well I can see you do not have a margin account as the funds you have not used are actually drawing dividends as the firm is using that money in other parts of their business. Just last year from E*Trade alone the dividend was $154. So your money is making money for you. Its called a sweep account. They take unused funds from your account and move them into "their" account to be used for other purposes. Is that money delayed in any way, no. It is still there and can still be used for purchases as well as withdrawal. Its just like a savings account.