Could you persuade your close friend to buy steem from Justin? I can't. Because I have no idea how steem block chain can survive without extra investments

Let see many unknown people invest a money to buy steems from Justin.

As you know we need excellent developers and marketing guys to finish SMT and better steem block chain. Then who will pay salaries for the these guys?

A witness is just a witness not people to pay salaries to them. We need a guy or group of people who can invest lots of money to realize the future of steem.