If you go a bit beyond the corporate-mandated annual security training, most information security curriculum says that step one is identifying the assets at risk and their value. It would be silly to spend $50,000 turning your garage into a vault to protect a $15,000 car, and similarly for information security the value of the asset determines the maximum effort you should put into protecting it. This not only avoids wasting more time/money/hassle than the asset is worth, but it allows you to spend your efforts on the most valuable assets. Any time/money spent on a low-value asset is time NOT spent protecting a higher-value asset.
The identity of your favorite gaming site is worth about 5 cents US, so it is error to spend more than 5 cents worth of time trying to protect that information.
Additionally, in most cases it is better to protect and encrypt data on a per-account basis, for both technical and practical reasons. On a laptop, that means you encrypt the home directory, not the system. Multiple user logins have separate encryption, and one account can't access the encrypted files of another account. If you want to take it a step further, you can have a work account on the machine and a separate account for checking personal email, etc. Along with the obvious security benefits, that avoids having the browser or search engine auto-complete a URL based on *personal* browsing history in the middle of a presentation.
Given per-account security, a guest account with restrictions on it is quite feasible, and a theif would likely click the guest account.