Down-to-earth means down-to-earth work and life.
The whole sentence means: the ideal is beautiful, but if it is divorced from reality, it is only beautiful, has no practical effect and is full of danger. I'd rather live a down-to-earth life;
Or: a certain life attracts people's attention (such as a star), which is dazzling and cool, but behind this life, people's hearts are empty, so I would rather live a plain life.
I hope it helps you. O(∩_∩)O haha ~