Paper money cannot preserve your wealth over time

I do not keep all my savings in precious metals, but, historically seen, cash has been a bad investment, and over time all paper money have lost their purchasing power. I hold some gold and silver, I am also on the board of directors of mining companies. I hold real estate, mostly in Asia, specifically in Vietnam. I hold some stocks - maybe 25% of total assets, and I hold some bonds in cash. So I'm diversifying, but an investor should realize that paper money will lose its purchasing power.