Dropbox and Google are not “competitors” to Bitwarden — you are comparing apples and oranges by bringing those up.
This amount of storage is included only in Keeper’s Family Plan, which has a subscription fee of $85 USD/year. Bitwarden’s Family Plan comes with up to 7GB storage included in the $40 USD/year price, of which 1GB is for shared files; you can upgrade this to 10GB storage for shared files (plus 1GB for each family member’s individual vault) for a subscription fee of $76 USD/year, which is more than 10% cheaper than the deal offered by Keeper.
And as already noted by @Nail1684 above, if you want 10GB of storage for an individual account, Keeper would charge you $52.44 USD/year, compared to Bitwarden’s $46 USD/year, which is again more than 10% cheaper than Keeper.