Everyone has regrets. Many may deny it, but we all have regretted something and still do, even if we conceal it with a veil of other thoughts. Sometimes this is beneficial, and other times it's detrimental. The majority of regrets are mistakes or decisions we make. Although many can be altered or appreciated (think how a mistake may add appropriate character to an art project), some cause us to wobble and maybe even topple over. It all depends on how someone handles the situation.
However, I do believe there is a solution to make all consequences less harsh than they initially are. If everyone in this world were optimists, think of what we could create and how our world could be different. This will never happen, but it's fascinating to ponder.
Conversely, if people lived in the pool of their regrets, how will life go on? Will it continue spiraling until the pool converts to a whirl pool, sucking all regrets and the regreter down into its depths? I think regrets should be taken seriously if they are, but most of the time forgotten. Our lives will be much more fulfilling if we live in "what is" over "what if" or "maybe...".