I noticed in the terms of service for Genesis Mining a statement about forfeiture of any credits, or payouts you have earned if the company happens to go out of business. Therefore, it would be prudent not to keep a large amount sitting on any website. Especially with hackers prowling around searching for a place to commit their shenanigans. Play it safe and get a hard wallet. When it comes to something as important as your finances there is no such thing as being too safe. Better safe than sorry.