I've read a lot of sci-fi about this.
First of all I agree, a copy is not you. Even if it's a perfect copy, which current science says is impossible, it's not the same person as you. I hate a story where somebody says "It's okay if I die, I'm backed up."
You're assuming that electronics are forever. Your brain has lasted your whole life. How many electronics have you owned? Of course you can copy the information to new electronics but there's still entropy. You can extend it for a long time but preserving information forever is really impossible.
The brain could be rebuilt and revitalized and expanded for a long long time if we had the biotechnology. You also assume you need to preserve a part of the biological brain to remain yourself. Eventually you could transfer your consciousness and memories to another medium or create technologies that are not too far from the human biological brain and body. You wouldn't be human anymore but living for hundreds or thousands of years or even more would change you so much it wouldn't even really matter if you were technically human anymore.
Also consider that if you're technically immortal you'd eventually die of a horrible accident, murder, or suicide.
Here's a really interesting video about it: