The same amount of gold which in 2005 cost 400$ now costs over 2000$.
That is about 5x increase.
So, if someone in 2005 invested 5000$ in gold, he would now have 25.000$.
If he invested 20.000$, he would end up with 100.000$.
However, if same growth continued for 40 years, then investing 20.000$ in gold would end up giving you 200.000$ after 40 years.
Thus, gold is probably a very good investment.
If you think about it, it is very practical. You can buy gold, and if you ever lack money, you can sell it at any time. But if you dont sell it, it rises in value to give you much more later.
With government printing dollars on mass scale, it is basically guaranteed that value of money will drop compared to commodities like gold, thus gold will only rise in value even more.
It pays off much more to invest in gold than to keep money in bank. It could even pay off to borrow money from bank to invest in gold, if interest rate is low enough. Basically, as long as you pay back somewhat less than double over 10 years, the value of bought gold will most likely be more than double after 10 years and keep increasing for years after. But I dont really recommend anyone to get loans from bank because banks are there to make themselves richer, and you will always give to the bank more than you took from it.
Now, value of silver isnt as stable.
Silver value increased about 4x in past 20 years, but it did experience many changes and sometimes at times even a drop in price, even if overall price increased compared to 2005.
I guess its nice to buy some silver too.
Land also greatly increased in price. Land in some places increased by 10x since 2005. However, when it comes to land, there are 3 factors at play. Rising population increases demand. Money printing also increases demand. But the location of land and the quality is what ultimately determines the price. You want desirable land, not something people wouldnt even buy.