Party goers are often healthy young people of which some part will become militarily active. By elimination of those people from the gene pool, you kill two birds with one stone. Also, the number of economically useful years of damage per victim is optimized that way and the investment made by the state in education is also maximally destroyed.

The train bombing in Madrid also falls within that pattern.

I thought it was more fore emotional effect "Oh, no, think about the children" and the fact they are relaxing exercises and as such destroy for example the tourist industry in some destinations like Bali.

Having said that, I suppose that blowing up one of those terrible tourist busses with a bunch of 70 year olds doesn't have the same emotional impact. In a way, it would argue for less security measures for older people, because that human capital is less valuable.

A party is almost by definition a dangerous place, because unknown people enter. Even without terrorists, I remember parties typically attracting assholes.

Your comment would totally be deleted in lots of media publications. I like the cold hard analysis. It provides further understanding for how the world works.

If I follow this line of thinking, it becomes quite easy to identify what likely next terrorist targets would be.

I don't understand how it was prepared two years in advance, but typically such parties aren't announced two years in advance or was there a version of that party a few years ago too? Also, two years ago there was COVID, so that would suggest they have been planning this for much longer.