I don't believe you can buy RTC after the crowdsale as they will be burned if unsold during crowdsale.
Yes, i think you will be able to buy RTC after the sale only on exchanges,but now its the time to invest,with this bonus.Early bird gets the worm
Understandably, the best time to buy a token is during pre-sale because of huge bonuses
True. It is best for investment but interestingly enough more people buy in later stages when they have had a chance to study more of the material, sometimes even a beta or MVP.