How does an E6 have 6 service stripes?

Bergdahl is a POS!!!!

I agree with previous response, sorta. The way you worded it, even proposing it, shows you did little to investigate this yourself. That does make this a stupid question. Service stripes can come from prior service, other services. All this indicates is that he had 18 plus years of HONORABLE, NO NEGATIVE ACTIONS TAKEN time in service. E-6 after that long, with those stripes, indicates he 1. re-entered service at some point, 2. Was in an MOS that had promotions maxed out. 3. Incompetent Command that intentionally held him back or locked him in a position due to special need or skill in that specific position.
In all 3 cases, kid, you are looking at a real man. Someone who due to forces probably beyond his control served 18 plus honorable years doing a job no one else could perform.
Instead of trying to stupidly vet him, you should probably be honoring the hell out of him.

SSG Ret. Special Forces

Trust me PFC, those stripes were earned. MOS dependant promotions, unit dependant, could have hit a bump in the road which you show me an NCO that hasn't and you'll color me impressed. He's got a hell of a stack going which shows me, that SSG didn't Dodge anything and does his job.

I wouldn't tread this trail.

A lot of MOS's dead end at E-6; not only that he could be in the NG or AR. My son's KYNG unit had a Unit Armorer that was about 45 years old and was only a SP4; but he loved his job and didn't want to move. On my 1st tour at FT. Hood, TX, I had a SSG that was a section leader and would have had to change MOS's to go any higher, but he really loved his job in the Welding Section. He had 18 years in and quit to work on the TX oil pipeline in East TX instead.

I retired as an E6/SSG with 24 years of service and 34 months of combat. I earned every stripe I wear.

I would guess a break in service. Stripes fly away real fast.

And your question is?

My old commo MOS had 998 points cutoff for 10 years.

See this is that mentality as a result of people getting promoted too damn fast on a regular basis. People expecting to make SFC in 10 years.

He stopped getting promoted. That’s about it. Whether it be a saturated job field or performance/behavior based it could be hit or miss and person by person. It’s not uncommon enough to make it weird though. There is a stigma about it in the Marine Corps and Army. More than a few times I have been questioned about retiring as a SSgt and they back off when I respond that I was medically retired with under 12 years. I won’t lie, it would be easier if I was a Gunny