Some problems:
* Centralization of mining seems inevitable.
* There is no mechanism to stabilize the value.
* Limited supply leads to expectations of high value which leads to hoarding instead of use.
* Block reward leads to a hyperdeveloped mining industry supported by investors rather than by users.
* For most people, irreversibility is a serious defect, not a feature.
* Risk of theft is too high for people who are not computer experts.
And maybe more.
Perhaps a million people have a reasonable understanding of bitcoin and believe in its eventual succeess. Probably millions of people also have a reasonable understanding of bitcoin but do not believe in its eventual success. The other 7000 million either haven't heard of it, or have heard of it but don't care to know more, or know just enough to dismiss it.