PE back to IB…

Few reasons and anyone who has been through any kind of MM shop in particular likely sympathizes here.

1. Fundraising: People lie, numbers don't - if you are the nth thousandth MM fund doing basic, undifferentiated services or industrials businesses, you likely haven't fared well in the post-ZIRP environment and the era of free money from churning dividend recaps and begging God for multiple expansion are gone... this makes actual investing much more difficult when you need true operational expertise to improve your portcos.
2. Promotion: As an analyst in banking I despised the politics that came w/ IB and thought PE would be a bit slightly better (w/o much reason) - I was wrong and it was even worse + PE has what I call the "carry traffic" problem - simply put, even if you are a PE god as an ASO, it doesn't even matter b/c the line for carry is massive and coupling that w/ bad performance means you have a low chance of seeing the little carry your MM fund would get if it even beats their hurdle rate. Check the PEI stats - DPI isn't looking good for most and this goes for any of the non-MF funds and even some MF funds like H&F.
3. IB is Arguably "Easier": Once you've done PE, IB from the outside in looks more understandable and you "get it" way better - you know what priorities actually matter, you come back with the "investor lens" (seems like a joke but it's legit) to understand businesses better, etc. you just have a better understanding of the investment life cycle in general and you're way more technical than your peers.
4. Stability: In IB, if you have a pulse, you get the A2A promote and looking back at when I was an analyst it was flabbergasting how lazy so many associates were... if you just care 10% more than the average ASO in banking, you'll do well. Beyond that, once you're an ASO 3/4 and def when you hit VP, you get the privilege of being more strategic + protected by bureaucracy + army of analysts under you to help... it's pretty sweet when put into perspective.
5. Higher Pay: Coupled w/ the above, you also just get paid more - objectively IBs pay more in base and while cyclical, you NEVER have to worry about performance... PE is stressful b/c you literally can't control if your portcos suck and many of them def will... in IB you make the fee regardless of whether the deal sells for a lot or a little (higher / lower fee, but still a fee!) and if it goes bankrupt then you can get an RX mandate! No way around that compared to hitting your hurdle rate

There's more reasons but those come to mind. Once you get past the groupthink of the buyside being everything you realize that IB, if you find a team of people you actually like + solid pipeline is amazing. Of course, if you go to GS or EVR you will want to die, but there are firms that balance things well.