Nominal return is not purchasing power
Compare a naira gain with inflation, fees and currency movement before celebrating it.
Diversification changes the dependency
One company outcome can be dominated by one management team, balance sheet or industry event. A wider basket spreads those company-specific outcomes.
Use this as a decision check
Can you explain both the purpose of the money and the downside without relying on a recent return?
A basket can still fall
Diversification reduces concentration risk, not market risk. Fees, inflation, currency and the actual holdings still matter.