[WhatDoYouThink?]

Same like bto them mop

TOP 30 months ( 2.5 years)
BTO and collect key (0 5 years)
Total 3yrs .
Stay another 5 yrs ( MOP) then can sell. 
Total 8years plus the progress of selling and buying and relocate to new home about  8.
months. So actual number of years is 8.8 yrs

that's a lot of opportunity costs. 8.8yrs can flip flop several rounds with private properties