As above, going all in on a move is a great learning opportunity however it plays out!
I think one of the most important things to learn in racing is that there is very rarely a “right” or “wrong” move, it’s about playing the odds, and the more experience you gain and the more things you try, the better you get at figuring out the odds. You’ll notice on the podcast that when Amber is asked a question about tactics she nearly always starts her answer “it depends”. And that’s because context is everything. What your strengths and weaknesses are, who you’re racing against, what the course is like, what’s already happened in the race, etc.
Attacking 1km out against a large bunch on a fairly straightforward finish? Almost certainly doomed. You might pull it off if you’re a lot stronger than the rest of the field, but if that’s the case then you could probably win in a whole bunch of different ways and tactics are somewhat immaterial. You might get lucky and a crash happens which takes out the chasers, though you probably don’t want to win that way. Otherwise it’s almost certainly going to play out the way it played out this time - you get swamped and finish nowhere. If it’s an attack from a break or against a thinned out bunch at the end of an attritional race? Much better odds. Add in a technical finish e.g. a chicane where being able to pick your line outweighs the disadvantage of being in the wind, and the odds are better still. A tailwind would help. Conversely, a headwind tilts the odds against you.
So don’t second guess the attack, learn from it. Which if the same situation plays out again probably means trying something different. Attacking further out. Or doing more earlier in the race to try and split it and avoid having 20+ riders still together at the finish. Or sitting in and trying your hand at the bunch sprint. Which is not the same as “settling” for top 10 instead of trying to win - could be that your “decent kick” plus some good positioning and timing is enough to win bunch sprints. You won’t know until you try it!
Also worth pointing out that part of the learning is figuring out not just what the best odds moves are, but what you want to get out of a race. It’s all very well for people to say that going for the win makes you a better racer than settling for top 10. But if you find yourself in races where you don’t have any particularly good chances of a win, and constantly trying high risk moves to win ends up with a string of low placed results, that can be demoralising too. In which case being a bit more conservative and getting some solid top 10s under your belt can give you the confidence to build on. I did a race series a few years ago where I came to realise that my chances of winning were slim to none. Big, strong fields with teams who actually worked together. I tried a bunch of different tactics (including the 1km solo flier!) and none of them worked, I kept rolling in exhausted and outside the top 10. Bit of consolation from other riders telling me I’d made the race more fun or open by forcing splits or opening up counterattacking opportunities, but nothing to show for it. So eventually I had a race where I just sat in and saved matches for the bunch sprint, even though I’m not much of a sprinter. Relied on the teams to close down the breaks and for the strong riders to tire themselves out. All came together before the end and we were rolling into the finish still with >50 people in the bunch from a starting field of >100. Got myself on the wheel of a guy who I knew would be there or thereabouts at the end, finished 8th and beat some very good sprinters. Did anybody else care that I’d finished top 10? I doubt it! But I’m still 100% convinced that that was about the best result I was capable of getting against that field at that time, so I don’t regret taking that approach for a moment. I also learned that I can hold my own in a bunch sprint against some pretty decent sprinters when I give myself the best chance of doing so, which has helped me get some good results in other races against weaker fields. And I learned that if I’m going to do races against fields of that calibre then I’d prefer to do so as part of a strong team (I was on a team at the team but my team-mates had even worse odds of winning than me!) so that if I can’t win I can at least get some satisfaction from trying to help somebody else to.