Teaching a "method" is not consider as collateral and for sure it's not convincing anyone.
Offer a valid collateral and maybe you will get something or if you don't have, just lock your request.
First,yep nobody will lend it to him because it can be considered a 'huge sum' and he did not say anything about collateral and based on his promises make it even more suspicious (even thought a lot of opportunities always happened if we're lucky enough).
Second,he did not say a 'method' as a collateral if you read it again carefully. Look at it 'if you do not believe me i can teach you how it works,but you need to give me my shares'.so,he's teaching you a method about that oppurtunity (arbitrage).
If you're sure about your method,try to open it in service board.you can find it in there,because a lot of people sharing about job and reward in there (that mean many people have a lot of bitcoin in that board)