That's a flawed way to look at it. It doesn't matter how what percentage of the whole pilot group leaves, it matters what percentage of the pilot group above you leaves. If you think that the amount of people who leave in front of you is going to stay consistent as you gain seniority, you're going to be disappointed.

For your 7 years to work out, that 30% you're counting on leaving.... they all have to be senior to you up until the month you flow. Ask yourself if that's realistic