I see two possible paths forward.
The less likely is to read and internalize http://www.mrmoneymustache.com/2012/01/13/the-shockingly-sim... and realize how quickly you can reach financial independence at a reduced spending level (but one that still affords an amazing life). Buying time is the most valuable use of money, IMO.
The second is to stay miserable for a while, striving for something ambiguous yet out of reach, until you get older and this feeling fades.
Path #1 (or a variant) is probably healthier and happier.
Also I have mixed feelings towards recommending the Mustachian community to OP. FI might help quench a thirst for money, but it also might just augment or exacerbate the obsession with accumulating money.
Personally, I see this problem as more of a philosophical one. I can't offer answers, but as someone who also has to consciously fight off obsession with money, practicing mindfulness, living in the moment, and finding joy in relationships and other "free", meaningful things helps. idk ¯\_(ツ)_/¯
If I am truly doing this, can that still be rationalized even when I am very underemployed?
While I won't bog you down on the details, I have a really patchy work history created by frequent layoffs. This created a lot of unemployment time, taking up about a quarter of my post-academic life. On top of that, I am very underpaid for a developer (~40% of the local average pay) so I often struggle making ends meet when I'm out of a job.
I feel pressured from many sides thinking of many possible solutions to choose.