On Colorado K0ne has 2121 hours of construction and only has 889k wort of construction points. So have fun
So 2121/24= 88
Now 88/0,66= 133
So you will waste 133 days of your life on that achievement
Actually that's only 889k so you waste a little bit more
as a little its 50 more days
Just a quick fact
Not so quick!
You can only work a limited number of hours every day, else your motivation drops. When the motivation is low, you earn less construction points.
You can increase your work motivation back to 100% by waiting for the day to pass, by using chewing tobacco that you craft or buy, or by using soap water that you purchase from the Union Pacific shop.
I'm unaware what's the recovery rate for construction work, and how much motivation you lose with every shift. Many years ago you could do 4 shifts/day of construction work while keeping the motivation high, and a pure builder could earn 600 construction points per shift. If things haven't changed, we're looking at 417 days of town building for 1 million construction points.
And don't forget the cash! If the town treasury is empty, you need to pay $240 for every 1 hour shift. At 600 construction points/shift, that's $400k. Not an extraordinarily high amount, but far from negligible.
Nowadays you can use nuggets to regain energy and motivation. Assuming you have unlimited nuggets for buffs, and work 24/7 building the town, it still takes 70 days.
Unless you can earn more than 600 construction points per shift...