Spending 100mil really isn't a lot in the grand scheme of things. In the business world and even in general, if you want to make money, you gotta spend money. The more you spend, the bigger the chance there is to make more in theory.
To put it into context :
Lets be conservative and say MS sell 50million consoles. That's 50million controllers. Each controller is $50 a pop. So :
$50*50,000,000 = $2,500,000,000
That's $2.5BILLION from $100million.
Also, most people will have 2 controllers over its lifecycle. So of that 50million that bought lets again conservatively say that an additional 30million are bought.
$50*30,000,000 = $1,500,000,000
So in a conservative grand total :
$2,500,000,000+$1,500,000,000 = $4,000,000,000
That's $4Billion in revenue. Obviously costs of construction etc will be deducted from that amount, regardless it's still a huge profit after that point.
Buisness 101: How to make profit.