“For where your treasure is, there your heart will be also.”
It is reasonable to suggest that our hearts would be in the same place as our treasure. What we treasure and what we love is often the same thing.
The problem with having our treasure/heart on earth is that it is not secure. The possessions we prize get lost or destroyed, the people we love die. Even the intangible qualities that we value like love, respect or security are unreliable. There is no safe place on earth to put your affection. But if we learn to value the things of God's kingdom, our heart is secure with Him.