Um, No.
Standard glycol based DOT-3/4 brake fluid has a tendency to absorb water over time.
This
Water compresses differently and can cause brakes to become spongy, it also can create acids that eat at components from the inside.
It also lowers the boiling point of the brake fluid, which increases the chances of vapour lock... which is bad.
DOT-5 brake fluid is silicone based, and is usually used for extremely high temperature applications such as racing. But has extreme disadvantages for everyday use, like the fact that it doesn't lubricate mechanical parts.
It also requires a thorough flush, as DOT-5 fluid doesn't contain the same quantity of corrosion inhibitors and doesn't disperse the water. Although if flushed to remove all the water it can provide better corrosion inhibition as it is not hygroscopic...
DOT-5 may also be unsuitable for use in cars with ABS (as far as I am aware all car manufacturers recommend avoiding DOT-5 if your car has ABS) - the silicone fluid can froth if the brakes are rapidly applied and released, leading to a situation very similar to vapour lock (bad).
To make the change if you truly wanted to you would have to drain and then clean the entire brake system as the two fluids are not compatible.
This. DOT-5.1 is compatible with DOT-3 or DOT-4, and ABS, and offers a higher dry BP than DOT-5, the drawback is that it is expensive.