Yes and no. While I see your point, it may hold true for % not actual $ -which is what matters to many:
In the case of the Oktava Movie Set and the MKH50, the price is 185€ and 1545€ respectively (at Thomann.de). even if you can resell the used Oktava at only 40% of its new price you will still be out far less than if you manage to resell the MKH50 at 80% of new price (which would be the absolute max I would personally pay for a mint product without warranty).
If you end up disliking the Oktava and buy the MKH50 you'd loose 111€ - compared to going for the MKH50 directly.
If you go directly for the MKH50 and dislike it, you'd loose 309€
The dynamics on the second hand market is different, of course. However, it requires that you are able to comfortably navigate it - otherwise it may be very costly for you.