Whether you can collect Cao's calligraphy and painting depends on your own situation and needs. Here are some factors that may need to be considered:
1. Artistic value: Cao's works have certain artistic value, unique creative style and certain popularity and influence in the industry. But artistic value is a subjective concept, and everyone's views may be different.
2. Investment value: If you regard Cao's calligraphy and painting as investment products, then you need to know something about the market. Generally speaking, famous calligraphy and painting have high investment return potential, but the investment risk is correspondingly high.
3. Personal preference: If you appreciate the style and personal charm of Cao's works very much and your financial ability allows, collecting his calligraphy and painting can also be a reflection of your personal preference and taste.
In short, whether you can collect Cao's calligraphy and painting needs to be considered comprehensively according to your own situation and needs. If you have any questions or concerns, you can consult professional art consultants or relevant institutions for more professional advice.