You miss the major factor in your compensation: pricing pressure due to supply/demand.
By removing all the junior engineers, you've fundamentally changed the market forces longer term and most people expect that to negatively impact you in the supply demand curve regardless of whether or not the statements you've made above are true, which they most likely are for senior engineers.
I would add the counterpoint, however, that HK housekeepers can live lives much better than some HK citizens.
Room and board is given to a housekeeper. That in and of itself can translate to thousands a month in rent and many times, are better living conditions than HK citizens can afford.