Maybe we switch over to other business/ Investment it could be real estate Business or other investment

. I still can't believe that you will be asking this kind of question when buying and selling in going on. This can only be possible if selling is not taking place in the market, that's everyone will now concentrate in accumulating bitcoin without attempting to sell but this is almost impossible as majority of the investors will be tempted to sell thier holdings some day. So the fact there is that bitcoin will continue to be available in the market, it will be there for you whenever you're interested to start your accumulating journey but I will advice you start early if you're still a no coiner.
When the last bitcoin is mined, there will be no additional bitcoin that will be made since it has reached its upper limit of production which will prevent circulation of bitcoin in the market and make it scares, the miners will only be earning from transaction fees to validate various transaction, since there is no more block reward, in other to maintain blockchain and in the bit to do these the transaction fees will become higher which will make the system stay secured since they will be responsible for covering the expenses and the miners will assist in approving transactions and this will increase the price of Bitcoin drastically that the common man will find it difficult to buy,by then the world will go back to her formal existence before the arrival of bitcoin.