most folks nowadays don't have any patience and blame it on the industry if they go without a sale for a while..
i haven't made a single sale the final 5 months of 2016, and could easily have started doubting myself.. but bamm!.. just alone in january & february of this year i have sold already 4 domains for at least low 4 figures to low 5 figures..
you really gotta be damn patient and keep on improving your portfolio in the meantime while not losing your faith although it may be hard at times..
ps: and keep the handregging to (future) trends & niches only which you really understand in and out from your own research..