George Washington was only in his early twenties when he participated in the French and Indian War, but he had high hopes to attain some significant benefits from his involvement.
First, Washington was an ambitious young fellow, and he really wanted a commission in the British army. As a member of the Virginia militia, Washington was all too aware of his inferior status in the eyes of the British regulars. Indeed, militia officers were looked down upon by British officers even if the latter ranked lower, and Washington couldn't stand that. To avoid it, he even went to the extreme of taking an unpaid position as aide-de-campe to General Braddock. Washington, however, never did receive that commission he was after.
Second, Washington had financial reasons to desire the French removal from the Ohio Valley. He and his brothers were shareholders in the Ohio Company, an organization to promote settlement in the Ohio Valley. The British had granted the company 200,000 acres of land, but the problem was, of course, that the French and Native Americans were already on it. Washington and the other shareholders had a vested interest in removing them so they could earn money from the sale and development of that land.
Third, Washington wanted military experience through his service in the French and Indian War. Under Braddock, he increased his skills in commanding an army, building forts, dealing with subordinates, writing orders, and practicing military justice. He read many military histories and manuals as well, trying to learn everything he could about military life and practice both through his studies and by watching the officers around him.