You’re using broad strokes to rule out individual investments, i.e. Mixing a top down approach with bottom up. Therein lies the problem
If you want to invest based on themes then you have to pick some trend that’s taking off and in India typically we just look at what happened a decade or two ago in developed markets and extrapolate that. Mobile phones, airlines, cars, etc.
But the bottom up analysis shuns the industry averages and looks at the individual players to determine their strengths. Nearly all the profits in the enormous mobile phone industry are captured by just one player – Apple. Now you can’t say that Apple is a bad investment just because nearly every single player is bleeding money.
So as a macro, airlines are a bad business, as a bottom up approach, generalizing it to “every airline is a bad business” will be an enormous fallacy.