I don't think anybody in kenya has stash of cash because they cannot wash it. Going by Kaburas and all those who've been arrested - & pursued - by Asset recovery - most of the money is immediately converted into Prados, Lands, Rental, Hotels and such business.The big drug dealing boys like Kariuki and Mwao who deal with drugs - basically own banks (see charter house) or bribe bankers - to clean the money for them.
Now top political dogs like Ruto, Uhuru and Raila...basically have two types of corruption...they receive cash directly from bahindis and locals....those I think are ones that are dished out...or re-invested back in politics. For the big deals..like 30B SGR money Uhuru....the top dogs..basically use the Mauritius and British isles or other tax haven....to keep the money and launder the money.
I think Mauritius has been the main place for Kibaki era thieves....this is when you start seeing Mauritius Equity funds...starting to invest in Kenya. You'll read about a Mauritius Equity fund investing say 2B in some company or buying shares. Others are invested outside kenya - because politicians - always want to have Plan B - incase they have to escape kenya.
The money is reflected as FDI - but I bet half of our FDIS - are our corruption money being brought back home.
So two main means...bribe or own a bank or a sacco & launder money for local small deals. For 10% of International Contracts - Keep the loot in tax havens, register an equity fund or venture capital - and comeback - and buy kenya companies or assets.
The idea that Ruto has 10B or so Kshs in cash is insane. Who'd risk that - what happens if it's get stolen or the house catch fire
On forexing the KSh - i see your point: it is practically impossible to forex the old notes. CBK formally asked foreign central banks to freeze KSh forexing from Jun 1st.
I don't think Ruto is the only target - he is only among the biggest. Too many drug dealers, wash-wash counterfeiters and tax evaders out there. Corrupt moneybags must have purchased lots of assets in the 3-month window at huge windfalls to the sellers. Either way they lose a major part of the loot in the short laundering period. I don't think Ruto will be "crushed" but this a heavy blow in the war of attrition.