They say [It is said] that travelling broadens the mind. I certainly agree with this popular saying as I am myself a keen traveller. Going to different, perhaps far-off places gives you an opportunity to expand your knowledge about the world and people.
["certainly" sounds better than "surely" here.
"It" at the start of sentence three -- it is too far removed from the first sentence to be used to refer to "travelling". We need to make it clear we are referring to "travelling".
The question is, which is the better way to travel: alone or with friends? The answer will vary according to personal preferences.
[New paragraph -- different topic: travelling alone]
There are those, including myself, who enjoy solitary travelling, while others find such an idea rather unappealing. I personally truly love long trekking trips. During such excursions, you have a chance to get away from it all, to reflect on life and ponder on more serious existential issues. Being alone and undisturbed on a walking track allows you to do that better than if you were with others. Some prefer this as a form of detachment from daily routine.
On the other hand, there are those who can’t imagine being completely by themselves while travelling. For bubbly personalities, for example, the sheer idea of being alone for a longer period is just inconceivable. They would feel rather restless not being able to open their mouth and talk to someone.
[Again start a new para for this -- change of tack.
The sentence starting "One of the reasons ..." is a tad overlong]
There is also the issue of safety. Some say that is more advisable, out of pure common sense, to be accompanied by someone while travelling, and being on one's own abroad is rather risky.
[Avoid using the same word twice on the same page. You have "sheer" twice within four sentences, so I have put "pure common sense.]
The answer to the question whether we should travel alone or with others depends on our personal idea of travelling. Nevertheless, I think that for most people it is [would be] recommended to have a companion. It is simply safer that way.