My question is whether the price of bitcoin is rising or is fiat experiencing a decline?
because someone on the internet I saw once said, house prices don't rise, fiat is the one that weakens every year.
People over-exaggerate things and the simple answer here is that Bitcoin as an asset has the tendency to appreciate in value, to the point that in just a year at a time, it could have increased in x5 of the invested value. But be careful as this is not the case all the time, there are times you would invest in it but might lose /5 of the money, so the knowledge and the time of investment matters. And for fiat, if you save it in the bank, the interest would not be as much as that of Bitcoin, and we all know how inflation is battling the economy, therefore it won't be able to retain the value as it were when you bought it like say 5 years ago.
so if you buy a house for 20k$ in 1980 then sell it now for 500k$, he says that the house is not going up but the fiat is going down.
that's why we see rising prices in commodities in the long term.
Are all commodities actually stable, but fiat is weakening or are there exceptions?
The person is saying nonsense about the house remark, an investment is an investment whether Bitcoin or property buying or anything, it's about making more money. If you invested $20k in housing and gained $500k, that means you have earned x25 of your investment, which is against inflation. Bitcoin can't do more than that, and real estate is an investment just like Bitcoin, it's your choice to invest in either of them. Don't mind them misguiding people that Bitcoin is the only hedge against inflation.
I saw Robert Kiyosaki say he owns 15,000 houses and doesn't like Bitcoin a few years ago, but recently I looked back at his interview when he said he bought Bitcoin, and said it was a valuable asset?
does he see that bitcoin is an opportunity?
Yes, he saw an opportunity in Bitcoin. Of late, the media is propagating the halving season of Bitcoin, this is the season when Bitcoin and other cryptocurrencies appreciate significantly in price. This might be what Robert Kiyosaki realized and trying to diversify his portfolio. But he can't sell all his property to buy Bitcoin.