Expeditions are a main draw.
As an "open universe" game, it helps to set your own goals. Many people work to find the "perfect ship". Others try to max out their frigate and fleet.
I decided to build a farm and mining operation that generates everything needed for top-tier manufactured goods. 20 min of base-hopping and crafting now nets me roughly one billion. This is enough to let me not worry about funds for a while.
Another fun thing to do is wander about with a friend. My brother and I routinely do derelict missions for fun.
It just boils down to "find what you enjoy doing and do that."