To preach Bitcoin as an investment, to exhort people to convert their fiat into Bitcoin may not be that effected, at least compared to just preaching Bitcoin. To talk about Bitcoin itself will probably convince more than when you simply talk about its price.

Bitcoin will probably grow more popular if we talk about decentralization, immutability, financial independence, transparency, and other features of Bitcoin than if we talk about its potential ROI. The former will attract solid supporters, the latter opportunists.