1. It's entirely possible that the trade deal won't get Trump anything he wants in the end because especially for Westoids, making promises is one thing while keeping them is something else entirely. "I know we said we'd buy $750B of this from you but... we just don't have the money or the need. So now what?" That's nothing new. Also, personal sentiment in Europe towards the US is destroyed. Europeans hate Americans and will consciously reject American products after this.
2. Even if not, I don't actually think this is a stupid move for the EU. The Western empire is comprised of the major arm in the US, the minor arm in the EU, and some small appendages like Canada, Australia, etc... This empire is in dire threat of being defeated by China. The empire took decades to build and is a lasting relationship; Trump is flitting. The power emitted by this alliance and empire is what gives Westerners an inflated position in the word, which they greatly enjoy and use to their advantage, something we Asians call White Worship. Neither the US nor the EU can create this alone, but together, they have created it when China was much weaker and they have reaped all of the benefits. If the Europeans told the US to fuck off and they will trade with China, Pax Americana, US dollar dominance, the Western empire all die together immediately, all because of the flitting insanity of Donald Trump. After Trump leaves office, even with an EU-friendly US president, they cannot put the empire back together because during the period of a US-EU break, China will have come into such a dominant position of power, nothing can be reversed. Pax Sinica will be in the door and no one can push it back out. So to prevent this regret that the EU and US will likely face together after Trump leaves, the EU decided to take Trump's lashes and accept that it will be eating American shit at least until 2028 because they fear that the other choice will have the entire global Anglo population, all of their children and grandchildren, eating Chinese shit for the next couple of centuries.