If NEM makes a high on a particular day even by 0.05$ USD, I would make 0.05x10000 = 500$ USD in a day if I sell all my coins at that price.
That is only your gross profit. If you want to know your net profit - the profit left after deductions, then take a look at what sir Silent26 said.
0.05x10000 = 500$ USD - Investment cost.
Just because the price of a particular coin pumps doesn't mean you can now convert it and sell. You should make sure first that its expected converted value is much higher than your capital as much as possible. If you don't keep this in mind then for sure you will get a negative outcome/ loss.
Going back to the topic, it's fine if you will buy alts since they are at cheap price but I don't think it would be a good idea if you will convert your btc in order to do so. You must maintain the value of your bitcoin especially these bloody days so if I were you I'll choose to keep it.