As I've posted in other threads, I've had significant seat time in a 3 as well as an S and materials selection is one of my biggest gripes (though road noise on the 3 was surprising, this wasn't the case with the S). The interior feels extremely cheap. It didn't feel/look like it was going to fall apart, I didn't see any huge panel gaps or anything, but compared to my M5, which I had owned just prior to driving the S, despite the cars being in a similar price bracket, the S had nothing on the bimmer in terms of interior materials selection and that "quality" feeling you expect at that price point.
On the 3, well, getting out of the Jeep, which is draped in leather on every surface and feels luxurious, the 3 doesn't. It feels like a Nissan Sentra or similar economy car inside in terms of materials selection, placement, design...etc.
I also owned an Audi e-tron for about a month (my personal version of the "mistake" this thread is about) and not getting the Luxury option was a mistake, though the primary reason for divesting myself of it was the fact my wife hated it and we both missed the SRT. That said, the Audi was leaps and bounds better than either Tesla in terms of materials, sound deadening, interior design...etc.
It ultimately comes down to what traits are most important to you. If you don't really want an EV (which should be a no brainer primary component of this decision-making process) then buying one is going to end up being a mistake. I definitely wanted an EV, and my wife thought she did, but we discovered that wasn't really the case. If you want the best range and neat-o technology and are comfortable with everything on a screen and how well the interior is dressed isn't of super high priority, you'll likely love a Tesla. If you like certain things like heads-up displays, a traditionally located cluster, physical controls for things and a very nice infotainment that supports CarPlay and Android Auto and range isn't top of the list, you are likely better served looking at some other marques like BMW, Audi, Porsche...etc.