Even if this current plotting comes to nothing, there are plenty of ways for investments to fail over 1000 years. Even if we assume that the system continues intact so that the accumulated wealth retains its meaning and is protected, and it isn't directly targeted by the government at any time.

Investments can fail, such as bank deposits (bank collapses), shares (company goes bankrupt), government bonds (government defaults), commodities (price fluctuations as they go in or out of favour.)

Theft can also occur, including by corrupt insiders (sometimes even legally, just by inflating their salaries to ridiculous levels.)

The chance of remaining intact for 1000 years seems very low.

Do we have any institutions to point to, other than the Roman Catholic Church, that have survived this long?