Background: About 8 years ago I bought a rather cheap tent (about 100 €) for up to 4 people. It's quite large, you can stand upright in it's centre and there's an awning almost as deep as the sleeping compartment. I used it like only two times, then stored it for six years at my parents because I moved to a big city and neither had space nor need for it.
A few weeks back I had need for it and took it with me on a one-night trip. Back in the day I stored it well enough, neither mold nor musty smells to be seen/sniffed. Still, shortly after we put it up, it started to rain for a short time and the tent almost instantly was drenched and started to drip. Also, the next morning even the dew had penetrated and it dripped a little bit inside the tent.
Leading to my question: Is it worth the hassle to try to waterproof the tent again? I am aware it would be a huge amount of work. Still, I am a bit appalled by the idea to throw away an otherwise intact tent which wasn't used that much.