(This is not financial advice)
Ignore the "be greedy"* part of the person you are replying to (although your hesitation is kind of proving their point a bit) but follow the advice of the Intelligent Investor.
When markets go up, everyone is happy to continue to invest. When they go down? People stop investing. That's precisely what you shouldn't be doing. Staying the course and continuing to invest regularly is key. When markets are sour that's when people get nervous and alter their behavior.
* Want to be greedy? Start buying Coinbase stock and Bitcoin. Notice how everyone is scared right now?