Like others have said, there are a few things worth spending dino bucks on, and many that are not.
Leveling up food production. I think the last two steps are 1000 and 3000 dino bucks.
Keeping your hatchery full. The first free spot is great for common/rare creatures with fast hatch times. The other three I fill with creatures that take days to hatch. Tuesday morning is hatchery speed up day. I think at most I’ve burned 20,000 bucks speeding up week long incubation creatures.
Creation lab for evolutions. It is usually cheaper to wait for the discounts to speed them up than filling extra tubes at 200bucks a pop (current price).
PVP play. 5 dinobucks a play. I played ten rounds today at lunch, came out around 200 bucks ahead.
Occasionally to speed up a dino cooldown to reuse a creature rapidly. This is probably more of a tournament/daily event thing if you are running out of time.
Occasionally a trade harbor deal for bucks is amazing. Usually not.