My point is that what Valve does with in-game items is similar to what certain mobile games do with time/pay-walls and how casinos exploit certain aspects of our psychology. And if you do not practice this "shady stuff", it is not that profitable…
# Crates
Crates or doubling, tripling, etc. item's cost. Say I want a certain hat, on average, I'll need to pay multiple times (crate contains 5 other items, but successive crates do not yield duplicates in most recent Dota 2 versions, so worst case you pay 6 times a price).
# Steam Marketplace
Adds at least 30% to item's cost, since you buy with real-world dollars, but sell for "Valve Dollars" (only usable in Steam, no withdrawals), this is effectively paying more for a single item (at least 30% more expensive which is Valve's margin for Steam purchases of non-Valve titles).
In addition, Valve makes purchases non-tradable via Marketplace for a period of time (multiple months, usually) since original purchases for "preventing fraud". I see it as "incentivising gambling with crates", though.
# Third-party site
These were probably shut down because they involved real money, so Vavle could be potentially helping organise casino/bookmaking businesses from legal standpoint. It's all fine with Steam Money from marketplace.
So, yes, it is extremely profitable, probably orders of magnitude more profitable than "honest" selling where transaction is "pay money, receive item".
# Regarding TI
It is incredible how much money it made. It is as incredible as how Valve decided to split matchmaking pool for months with International Ranked to boost prize pool, so you had to pay $10 to go into faster queue.