Tesla is clearly flying close to the sun, and Musk is not incorrect to suggest that investors who can't take that kind of risk should not be along for the ride; however, it probably would have been more prudent to hold back on that pronouncement, given that many investors seem to have taken the hint and exited the stock... Tesla is a giant confidence game - as are most high growth opportunities.
Under these circumstances, it is not unreasonable for investors to hold you accountable and inquire about the financial situation and plans. Musk's conduct was unprofessional and he could have handled those questions more gracefully instead of dismissing them and berating the people who had been asking them. This kind of behaviour does not exactly inspire confidence, and burning your bridges with the very banks that you might need to raise money later on was certainly not his smartest move.
[1] https://seekingalpha.com/article/4169027-tesla-tsla-q1-2018-...