Strictly speaking, if he borrowed money from you 6 months ago (so let's say in March), then the price of BTC was identical to today's at the beginning of the month, but at the end of the month, it approached almost $60 000. It is possible that your friend has not made any profit, or that as an inexperienced crypto trader he has lost most of what he borrowed from you.
Probably the exact date when the purchase in BTC was made would prove to be the most important thing.
The vague term of 6 months could mean he has bought at either below current prices or above 55k, it's a matter of a week or so, and if he has bought over the current price, and given the fact that this discussion between friends has probably also started a bit in the past before the user has decided to share his story, so probably when we were under 40k it makes me think that the so-called friened is currently at a loss even with his trading and it's hoping for a bull run to come even, especially since he has invested a bit off the money in a laptop.
As for hiding the profits, unfortunately, there are so many ways his friends would be able to cheat him out of those, there is no way to be able to track everything he has done if he has used multiple websites and wallets and a lot of pairs tracking only the movements, not the profits made at the end of the story would be an impossible task.
But, my hunch is on zero profits as we speak.
Anyhow, assuming he has extra money and he is hiding from him, what would OP do about it? Go to court over a verbal agreement?