My mother said that when any of us kids were being at our least lovable was when we most needed loving, and that sometimes the hardest part of parenting is seeing past the topline behaviour to what’s underneath. I was struck by the use of “strut” in the first post- ime strutting in young men is pretty much always masking insecurity and/or fear. The more confident they are, the less they need to strut
The stepson has been living as an adult for a number of years- but the military is an odd kind of independence for a young adult: you have a lot of responsibilities, but there are also lot of rules / systems / structures Now he’s home, and clearly stuck.
OP, it may be more productive to look at your stepson as a young adult in trouble, vs a willful / selfish / lazy / liar / taker. You might do a little research on video game addiction and see what you find, but I particularly suggest that you call in reinforcements. Start with what you do know: the family is not in a good place as a whole, and some outside expertise could make a difference. You can own your part in it- your unhappiness at the current family dynamic is enough of a reason for your family to support you by all going to counseling together. It is a natural part of family counseling for there to be some individual sessions as well, and that might be the door into getting your stepson some help to get moving again.