No. All Sets that you obtain through TokenSets are held in your own wallet - including Social Trading Sets. All transactions that move your funds must be confirmed by your account and are verifiable on the Ethereum blockchain.
Underlying Collateral Tokens - The Vault Smart Contract
The underlying collateral tokens that back each Set are held inside of the Set Protocol vault contract. Traders and the Set team do not have access to your funds when it is inside of the vault contract. Only you have access to your funds in the Set Protocol through your Ethereum wallet. Because of this, it's important to note that if you lose access to the wallet that holds your Sets, the Set team will not have any way of retrieving your funds for you. As a best practice, keep your private wallet access information backed up and secured in a safe place in case of an emergency situation.
Social Traders cannot act maliciously
Set Protocol's Social Trader smart contracts ensure that traders cannot act maliciously against users.
Traders cannot rebalance into arbitrary cryptoassets
Traders cannot manipulate users trades (all trader and user funds are pooled together for rebalances)
Traders cannot arbitrarily adjust fees anytime. There is a smart contract enforced 7 day timelock before any fee change is approved
Users will be able to monitor any trader's skin in the game on TokenSets
Users can join and withdraw from the Social Trading Set anytime