smart investors will only make Bitcoin their main investment, and when they need money, they will use the Bitcoin they have as collateral in a lending platform, they are very smart because they realize that there are only 21 million Bitcoins and the amount cannot be increased or decreased.
No, no, no! Anyone using his bitcoin investment as a collateral is no worth regarding as smart because it makes no sense using your bitcoin to take loan on fiat. This is why we are advised to while planning on investing for a long time we also have a reliable income source if possible a stream's of income in order to avoid finding yourself in a messy situation where you would have to make such unwise decision because it's like telling an investor to stake his bitcoin for an altcoin.
How the discussion moved from buying bitcoin for long term holding to loan is what baffles me. The discussion have completely shifted to a new ground that is more or less a distraction. Why would someone doing DCA, for instance, consider taking a loan? The mere though of it simply means that the investor does not really have the cashflow needed to sustain a bitcoin investment for long term so investing in bitcoin may not be the best decision for him but to fix the cashflow. To succeed in bitcoin investment, there should be plans for emergency fund which will serves to keep the investment going when there is some development that requires money which was not seen or planned for in beginning. Without emergency funds, the investment is continuously exposed to risk. Taking a long is never in any of the process of healthy bitcoin investment.