Both left and right wing socialism have a tendency to collapse into dictatorships. In essence that's what socialism is, the dictatorship of individual behaviour by society. Left wing socialism has collapsed into Communism, more specifically usually a Stalinist or Maoist state. Right wing socialism also tends to collapse into dictatorships, such as National Socialism, Italian Fascism, Franco's fascism, Somoza, Pinochet, etc.

So each system is inherently unstable, and there is no pure form of either that isn't bad, because an absolute form is an absolute control of the individual by society. The best way to avoid this is a kind of balance between the two forms of socialism, where they squabble over helping the right wing constituency or the left.

The second part of the balance is the Libertarian balance where the individual is supreme over society. This also has two sides, to help the right wing or left wing people. The libertarians typically push for more freedom for the right, for example to have more guns, deregulated business, lower or no taxation, etc. The left wing libertarians push for more rights for the left wing constituency, such as rights to take drugs (which is mainly a lower class crime), civil rights (such as the ACLU), and abortion rights.

The best balance is somewhere in the middle of these 4 extremes. This balance is to some degree self correcting in a democracy where if the system starts to favor one of the 4 aspects then the other 3 are left out of the benefits more and more, and vote for someone who includes them more.

History however has shown there indeed are slippery slopes towards both left and right wing socialism, and it is very difficult to come back from it. In the same way if the individual on the right or left has too much supremacy over society it is also difficult for the system to come back into balance.

For example the fight over abortion is a struggle between left wing libertarianism (left wing individual triumphs over society) and right wing socialism (right wing social attitudes triumph over left wing individual). Gun laws might be a struggle between right wing libertarians against left wing socialists. Tax law is a struggle against right wing libertarians versus left wing socialists who want to spend it on welfare for their constituency. Drug laws are a struggle against left wing libertarians against the right wing socialists (where the wealthier society tries to keep drugs away from its community by jailing poorer individuals).