The coin tossing theory is a good one and has been associated with technical graphs for many years.
In principle the more times you flip a coin the closer it will get to being 50-50.
This theory is based on an individual person with no mechanical aids or manipulation, trickery or machine. It can however be used under any circumstances, randon rooms, temperature, weather conditions ect. If unsure then reach for a coin and try it keeping notes of the flips.
This is where graphs, moving averages(MA), market strength(RSI) ,fear ,greed and probability can be taken advantage of in the markets.
Now in theory theres no law to say I cannot flip a coin and get heads 100 times, however, this is unlikely to the extent of impossible over many lifetimes of constant flipping. It's not to say it wont happen but it's improbable.
If I were to flip a coin day in day out it's likely that at some point during the day/week month I'll flip 8 heads in a row, now although in theory the next flip has a 50% chance of being tails, the probability of this is far lower as over time I must get 50% heads to tails. So, probability of the next flip becomes more in the favour of being tails. If not the next flip, or the next flip and so on.