All Fights end up on the Ground?
If You mean when one of You is laying on the Ground with Broken Bones, then Yes.
Or if You deliberately Train to try and make it that way.
Also, the idea that a Fight comprises of someone standing out of range then throwing Hooks until theyre close to You makes Me wonder where You get Your Information
As for People Fetaling up, thats just them being Afriad.
In Response, BJJ will Help You as long as You realise that Your Opponent is not going to Wrestle with You. Hes going to Hit You and Hit You and Hit You whilst You try to Wrestle Him.
Unless A: You use Takedowns, over actually Wrestling.
B: You use a Choke. Because Jointlocks might work, or they might just seriously annoy Him.
Your first thought might be MMA.
In MMA, Youre not allowed to Hammerfist someones Spine whilst they try to do a Double Leg Takedown.
Theres alot of Angles to this, so Ill simplify it.
If You are more comfortable with Grappling than You are with Striking (More Comfortable with. Not "I like one more than the other"), then You will benefit from BJJ in an SD sense.
Because in SD that isnt some stupid pretend Brawl, it very quickly degrades into Senseless Violence. It is not Sparring.
As such, You will do whatever Your Instinct tells You to do. And if thats Punch, when Youve Learnt to Grapple, then You may as well have just gotten Fit instead of actually Learn BJJ.
If Your Instinct is to Grapple, You will not do half the Stuff You Learn. But You will be better at Grappling.