When deciding what level of hosting I need – the power of the machine – I ask my techie; there's no way I can figure it out for myself.
For example, I've got a shared hosting plans with eight or 10 websites hosted and no problem.
For a product launch I did a few months ago where I sold 800 units I used a VPS, which my techie told me would be plenty. For my next launch I expect to shift 5-10,000 units. If I do this as a big bang launch I will have to do decide whether the VPS has enough guts to handle may be hundred thousand visitors over a couple of weeks without crashing. I really don't know - that's what techies are for!
On the other hand, 5 to 10,000 people accessing the membership site which delivers the finished product will be much less of a strain on the server I use. So, again, it's a question for my techie.
It's horses for courses and only a techie – someone with more knowledge than me – can judge the suitability of your server for a particular task.
One thing is sure; your server falling over mid-launch is very bad LOL