I would suggest you to be prepared to jump out again. The most important rule in speculation is: to have a plan (specially: to have a stop price where you should sell if things go wrong) and stick to it.
Most people lose money because they hate to accept a loss, so they keep the position on hope, converting a speculative short-term/median-term move on a long term negative bag-holding. Accepting losses is the test for any trader.
Or, at least, buy in increments, saving a few to real low values, just in case.
Bold:
I think this good advice. After the recent rise from $340 to over $540 I should have set up a plan, something like "If it drops back to the $460-480 range, the trend is not reversed and I should sell and wait for a lower entry point". Perhaps I will set up a better plan than I have now. However, the probability (in my head) of the price going lower than $260 seems low.
Italics:
The worst (not really the worst...) part of selling at $430 is knowing that I wanted to sell earlier but didn't. Your sentence pretty much sums up me as "most people". Though I don't have a lot of coins (relative to most on this sub-forum) and that I haven't invested more than I can lose, sealing in a $1000+ loss was not fun. It certainty would have been easier to hold, but I'm hoping it will be more profitable to have sold.