Last October I did 4 nights in the Smokies and it rained hard every single day. My fancy tent from two seasons ago soaked through the seams by night 2, but the cheap blue tarp I strung over my cooking area stayed bone dry the whole trip. I spent $30 on that tarp at a Walmart in Gatlinburg, and it did more work than the tent that cost over 13 times as much. That tent is now retired to car camping duty only, and I just use a basic footprint and tarp setup for solo trips. Am I the only one who thinks the gear industry oversells waterproof ratings? What's the cheapest piece of gear that beat out your expensive one?
Did you actually seam seal that tent before the trip, or did you just trust the factory job? I got burned the same way once, so now I reseal every new tent before it sees rain, but I still carry a $10 tarp as a backup. The real question is why we accept that a tent needs extra work or a tarp over it to do the basic job of keeping water out. Waterproof ratings are marketing numbers, they don't tell you how the thing holds up after a season of use. Cheap tarps win because they're simple, no zippers, no coated fabric that wears off, just plastic and grommets.