you should also know that mbtc has no value and they want something that they could hold unto.
This is a wrong idea Aanuoluwatofunmi who said mBTC has no value? In the contest Op hosted, he was actually offering 1mbtc as the first price for the contest of which as of the time I am writing this is equivalent to $70.
No matter how small or large any amount of Bitcoin is, it can still be expressed in mBTC. The only significance is that it is more efficient in smaller units of Bitcoin. mBTC simply means a Bitcoin into a thousand units . So instead of using decimals to express 0.0008 Bitcoins you can simply say 0.8mBTC.
I'm not sure this is what he meant. I am sure he was trying to say they probably did not participate in the contest because they felt the reward was too small. As it is common to find contest in the forum with prices a little fancier that that sometimes.
And large amounts of Bitcoins are expressed as regular Bitcoins not in mBTC because it will be irrational to say 1000mBTC when you can just say 1BTC. Therefore you can definitely conclude that mBTC is used in cases of just a few 100 dollars.