Depending on how far you get, it can be. My retirement without disability will be approximately 50k a year. That, plus disability in a LCOL area is enough. Retirees also get COL adjustments annually.
Current plan for me is to retire, attend law school, and work as a public defender to put my money where my mouth is as a filthy lefty, but the work is because I want to, not because I have to based on where I’m planning on retiring.
At 20 years, every active duty service member can retire with 50% of their highest three years of pay for the rest of their life. They also get evaluated for disability, and get that for the rest of their life. After 20 years, each year served adds 2.5% to their pension, so at 30 years, they would get 75%.
How much that pension adds up to depends on how high you moved up in the ranks. A 20 year enlisted servicemember will make a lot less that an officer. More senior enlisted will make a fair amount more than more junior enlisted.
Disability pay is based on how big of a mess you are physically and mentally, each disability pay band is the same, regardless of rank.