I'm not sure requesting investment advices on a forum is a good idea. You have half a million bucks - maybe request the help of a professional or use your own time to do some research and see what your best option should be?

Bitcoin has always stayed up the most and the best. Besides this, nobody really knows an accurate answer to how much we should wait or how deep a dip will look like in the current market conditions. Crypto markets are new. We're still early birds, and the conditions of the market change second by second..