Oh my goodness. Well, I can relate. I spent the first year of Angus' life in tears. I would dread coming home, and just sit in the driveway, thinking, "Oh dear Lord. He's in there. I don't want to go in."
Like yours, he had another dog, our previous dog, that he had to live up to. And I considered Crash to have been the perfect dog (and puppy) from day one. I couldn't understand how a dog could do some of the things he did. There must be something wrong with him. Brain tumor? Rabies? These were both things I gave some serious consideration at various points in his puppyhood. I feel strongly that I can guarantee you that your dog is NOT worse than Angus was.
However, as Melissa said, one thing Angus never was, was hated. Oh, I had people telling me left and right, for months, that I should take him back to the shelter, or "find him a nice farm to live on."

But as much as he was making my life truly, TRULY miserable, I had made a commitment. Angus didn't ask to go home with me from the shelter. He had no choice in the matter. I had a responsibility to do my best to be a good steward of his care.
One night, as I was wailing like a banshee that I missed Crash, my husband found this forum and said, "These people seem like they know a lot about Labs, honey. Why don't you join and see if they can help?" My first post was somewhat similar in tone to yours, and got about the same kind of responses. LOL I took my licks and explained that I didn't *really* want to kill him, that I was actually a nice person who was just at the end of her rope and desperately, desperately needed help.
They helped me. God bless them all.
Angus is five now. Is he perfect? Noooo. Is he Crash? Nooooo. Do I love him? Oh my gosh. More than anything. He has stolen my heart like no other.
It can be done. As others have explained, it is a lot of work and you have to be willing to put in the time. Training is never over. We started obedience training when he was a puppy, and he now competes and has four Rally and Obedience titles and a dozen or so ribbons to his credit.
However...I don't have kids. The dogs are my kids, and they are almost as much work as I imagine children would be. Daily training sessions, dog sitters at lunch to play fetch, hubby walks 2x a day, I play fetch with them nightly. All this to meet those aforementioned exercise needs. As you said yourself, "The only time he is good is when he's exhausted." Bingo. Welcome to my world.
So. I don't know...maybe you are like me, and were just having a really bad day when you wrote this. Maybe you could turn things around with a little help. Or maybe Labs are really not the right breed for you. I do realize it can be quite a rude awakening, if you've been used to a different personality in a dog, to have to adjust to the energy level a young Lab exudes 24/7.
I will say that it will get better from 10 months. I will also say that you are going to have to put a significant amount of work into shepherding the process. Are you up for this? Only you know the answer.
Both ZoeZoe and Dani (and I may be forgetting someone else who has responded) are actively involved in Lab rescue and can help you find another home for him if that's what you choose. Please don't take him to a shelter - the shelters are overflowing with Labs just like him, for similar reasons, and he will very likely never see the outside of the shelter again.
Please check back in. I hope it all works out for the best for everyone.