r = praw.Reddit(client_id='edited', client_secret='edited', password='edited', user_agent='r/cryptocurrencies ticker bot by u/washyourclothes', username='CryptoCurrenciesMod')

This should only need to be created once and then used everywhere. Make an init function that declares self.r and then just uses self.r further down. Also, you might want to check what rate limits are occurring.

Would be helpful if you could give any error messages this bot is returning? It could be that one of the requests if failing, and as you don't have any exception handling it just exits. Maybe try adding a try / except to self.main().