Relationship between Ethereum marketcap and marketcap of tokenized assets?

Lets imagine $10 trillion of real world assets are tokenized on Ethereum (custodially - e.g. Blackrock creating tokens backed by actual units of stock held in their books).

I appreciate that tokenizing these assets on Ethereum doesn't intrinsically increase the market cap of Ethereum - the tokens are just tokenized representations of underlying assets, they are not eg. pegged to a certain amount of ETH.

However, in order for this to be secure, does the market cap of ETH need to be e.g. 5x the market cap of the real world assets tokenized on the chain in order to provide the level of economic security required to make a 51% attack on the network economically unviable?