Let's take some extracts from Language and Symbolic and Power:
The constitution of a linguistic market creates the conditions for an objective competition in and through which the legitimate competance can function as linguistic capital, producing a profit of distinction on the occasion of each social exchange.(Bourdieu 1992: 55)
The dominant competence functions as linguistic capital, securing a profit of distinction in its relation to other competences only in so far as certain conditions (the unification of the market and the uneven distribution of chances of access to the means of production of the legitimate competence, and to the legitimate places of expression) are continuously fulfilled, so that the groups which possess that competence are able to impose it as the only legitimate one in the formal markets (the fashionable, the educational, political and administrative markets) and in most of the linguistic interactions in which they are involved.
It is for this reason that those who seek to defend a threatened linguistic capital, such as knowledge of the classical languages in present-day France, are obliged to wage a total struggle. One cannot save the value of a competence unless one saves a market, in other words, the whole set of political and social conditions of production of the producers/consumers. (Bourdieu 1992: 56-7)
Bourdieu, P. (1992). Language and Symbolic and Power. Cambridge: Polity Press.