because it has significant risks for now, that bitcoin doesn't
- iota is still centralized working with a coordinator. Until we see it work without, we don't event have a proof of concept
- wealth is currently in hands of very few people. Iota was poorly distributed which may create liquidity problems later
- there are unresolved technical problems - see transactions hanging for days, balances that need to be recovered routinely, etc
- there was big snafu on the technical side where they decided to roll their own encryption algo, which in the security/technical world is a capital sin. A lot of credibility was lost with this