This game is intense and you work so hard to achieve your goals that post-goal blues are almost inevitable - I used to get it when I collected enough DNA to get Stegosaurus up to Level 15 (“how am I ever going to get enough DNA for 16?”) and now I have a L27 Stegodeus.
November-ish I felt “the blues” big time (some may remember my thread “where to we go from here”) but then went on a superb run unlocking Diloracheirus, Magnapyritor, Turoramoloch, Thoradolosaur, Tenotorex, Tyrannolophosaur (thank you Sand Dunes!) and achieving my highest trophy count - and had fun doing it (not so-coincidently dropping Discord and spending less time on here at the same time).
Now post tourney “the blues” are back - of my four remaining creatures to create only one is unlocked and that has a miserly 10 of DNA - looks like a long haul. But hey, been here, done that - bring on the next update and the next wave of play